Electroluminescent material, electroluminescent element and color conversion filter

ABSTRACT

An electroluminescent element is disclosed, comprising an electroluminescent material and a fluorescent substance emitting light having an emission maximum at the wavelength different from that of light emitted from the electroluminescent material upon absorption of the light emitted from the electroluminescent material. A color conversion filter is also disclosed, comprising a fluorescent substance emitting light having an emission maximum at the wavelengths of 400 to 700 nm upon absorption of the light emitted from the electroluminescent material.

This is a Divisional Application of application Ser. No. 09/466,949filed Dec. 20, 1999, now U.S. Pat. No. 6,656,608.

FIELD OF THE INVENTION

This invention relates to an electro luminescent element, specificallyrelates to an electroluminescent element useful in a civil or industrialdisplaying device such as a light-emission type multi- or full-colordisplay, or a displaying panel, and color image forming method and acolor filter (color conversion filter).

BACKGROUND OF THE INVENTION

Electronic display device include a light-emission type and alight-receiving type. Examples of the light-emission type include a CRT(cathode ray tube), a PDP (plasma display), an ELD (electroluminescentdisplay), a VFD (fluorescent display tube) and a LED (light-emittingdiode).

Among them, the LED will be described below.

The LED is a light emission element comprising a light emission materialemitting light in an electric field or combination of several number ofsuch the element. The elements are classified into an organic elementand an inorganic element according to the material and into a carrierinjection type and an accelerated electron type according to the lightemission mechanism. The recombination of an electron and a positive holeis utilized in the carrier injection type element and collision energyof an accelerated electron is utilized in the accelerated electron typeelement. Generally, the inorganic material is longer in the life timeand more stable than the organic material. However, it is a shortcomingof the inorganic material that the choice of the material is narrow andthere is a limitation on the molecular design thereof. The recombinationtype has advantage that the driving voltage is lower than that for theelectron accelerate type. Recently, therefore, the carrier injectiontype LED is extensively developed.

The LED include the following three types.

(1) Inorganic LED comprising a inorganic compound such as GaN and GaInN:the light emission mechanism thereof is recombination type. It is simplycalled also as LED (light emission diode).

(2) Organic LED comprising an organic compound such as a triarylaminederivative and a stilbene derivative: the light emission mechanismthereof is recombination type. It is called as an organic EL(electroluminescent or OLED.

(3) Inorganic EL comprising an inorganic material such as ZnS:Mn andZnS:Tb: the light emission mechanism is the accelerated electron type.It is called simply as an electroluminescent element since the elementof such the type is historically old.

The “electroluminescent material” in the invention includes theabove-mentioned (1) and (2). Therefore, (3) is not subject of theinvention.

In the field of the carrier-injection type organic electroluminescentelement which has been particularly noted in recent years, ones emittinghigh luminance light have been becoming to be obtained after a thinlayer of organic compound has been used. For example, U.S. Pat. No.3,530,325 discloses one using a single crystal of anthracene as thelight-emission substance, Japanese Patent Publication Open for PublicInspection (JP O.P.I.) No. 59-194393 discloses one having a combinationof a positive hole injection layer and an organic light emission layer,JP O.P.I. No. 63-295695 discloses one having a combination of a positivehole injection layer and an organic electron injection layer, and Jpn.Journal of Applied Physics, Vol. 127, No. 2, p.p. 269-271, discloses onehaving a combination of a positive hole transportation layer and anelectron transportation layer. The luminance of emission light isimproved by such the means.

Besides, a fluorescent substance has been known, which emits fluorescentlight by absorbing light emitted from the electroluminescent material.The method using such the fluorescent substance to emit various colorslight by means of an electroluminescent material is applied for the CRT,PDP, VFD, etc. However, in such the case, there is a problem that lightemitted from the electroluminescent material must be a high energy ray(i.e., short wavelength emission) such as an electron ray or a farultraviolet ray. The fluorescent substances described above areessentially inorganic fluorescent substances. There are known a numberof the inorganic fluorescent substances which are superior in stability,exhibiting long shelf-life. However, there has not been found a longwavelength excitation type inorganic fluorescent substance exhibiting anexcitation wavelength in the region of near ultraviolet to visiblelight, specifically, red light.

A near ultraviolet ray capable of being emitted from theelectroluminescent material is contemplated to be a light having a peakof wavelength within the range of from approximately 350 nm to 400 nm,and the use of an organic fluorescent dye as the fluorescent substancecapable of excited such the near ultraviolet ray is disclosed in JPO.P.I. Nos. 3-152897, 9-245511 and 5-258860.

However, it is known that the organic fluorescent dye is generally tendsto be influenced by the circumstance condition, for example, change inthe wavelength or quenching tends to be occurred depending on the kindof solvent or medium such as a resin.

In the methods disclosed in the foregoing publications, a fluorescentdye which absorbs light of blue or blue-green light region emitted fromthe electroluminescent material and converts the light to red light. Afluorescent conversion layer which emits light in green region hascharacteristics that the Stokes shift (the difference between thewavelength of the absorbed light and that of the emitted light) issmall, and a part of light emitted from the electroluminescent materialcan be permeated therethrough, and the light from the light emissionmaterial can be converted with a relative high efficiency. However, theconversion to the fluorescent to light of red region caused problemsthat the conversion efficiency is considerably low since a large Stokesshift is needed and the light from the light emitting material almostcannot be utilized. Exemplarily, the combined use of a few fluorescentdyes different in excitation wavelength is needed and it is necessary toutilize light-to-light conversion (i.e., photoluminescence) of pluralfluorescent dyes, such as a fluorescent dye emitting yellow light inresponse to blue light and a fluorescent dye emitting red light inresponse to yellow light.

Accordingly, there is a problem that the visual perceivability and theluminance of color displaying by such the element are lowered since theluminance balance between blue, green and red light emission isunsuitable and the above-mentioned quenching and decoloration areoccurred.

The inventors can obtain an electroluminescent element capable ofemitting a high luminance light and having a high storage ability, andcan provide a color filter with a high luminance by the use of such theelectroluminescent element.

SUMMARY OF THE INVENTION

The above-mentioned object of the invention can be attained by thefollowing constitution:

(1) An electroluminescent material represented by the following FormulaN1:

wherein Ar is an aryl group; A is a carbon atom, a nitrogen atom, asulfur atom or an oxygen atom; X is a group of atoms necessary to form a5- or 6-member nitrogen containing aromatic heterocyclic ring togetherwith A and N; Y is a group of atoms necessary to form a 5- or 6-memberaromatic hydrocarbon or aromatic heterocyclic ring; the bond of C—N, C-Aor C—C in the formula is a single or double bond; and R is a hydrogenatom, a substituent or Ar; provided that the nitrogen-containingaromatic heterocyclic ring represented by

and the aromatic hydrocarbon ring or the aromatic heterocyclic ringrepresented by

each may be condensed with a hydrocarbon ring or a heterocyclic ring.

(2) An electroluminescent material represented by the following FormulaA1:

wherein Ar₁₁, Ar₁₂ and Ar₁₃ are each an aryl group or an aromaticheterocyclic group, and a biaryl group having a bond capable of givingat least two internal rotational isomerism is in the molecule of thecompound represented by Formula A1.

(3) An electroluminescent material represented by the following FormulaA2:

wherein Ar₂₁, Ar₂₂ and Ar₂₃ are each an aryl group or an aromaticheterocyclic group, each of which has a bond exhibiting C₂ rotationsymmetry and capable of giving an internal rotational isomerism.

(4) An electroluminescent material represented by the following FormulaA3:

wherein Ar₃₁, Ar₃₂ and Ar₃₃ are each an aryl group or an aromaticheterocyclic group, provided that at least two of Ar₃₁, Ar₃₂ and Ar₃₃are each an aryl group having a 1,1′-binaphthyl moiety.

(5) An electroluminescent material represented by the following FormulaB1,

wherein Ar₄₁ and Ar₄₂ are each independently an aryl group or anaromatic heterocyclic group; L₁₁, L₁₂ and L₁₃ is each a group of atomsnecessary to form an aromatic heterocyclic ring, provided that at leastone of L₁₁, L₁₂ and L₁₃ is ═N—, —N(R₄₁)—, —S— or —O—; R₄₁ is a hydrogenatom or a substituent, provided that at least one of Ar₄₁, Ar₄₂ and R₄₁is a biaryl group having a bonding axis capable of giving an internalrotational isomerism or a group having such a biaryl group, and theadjacent substituents may be condensed with each other to form asaturated or unsaturated ring.

(6) An electroluminescent material represented by the following FormulaC1,

wherein Ar₅₁ is an aryl group or an aromatic heterocyclic group; n is aninteger of from 0 to 6, the plural groups represented by Ar₅₁ may be thesame or different when n is 2 or more; L₂₁, L₂₂, L₂₃, L₂₄, L₂₅ and L₂₆are a group of atoms necessary to form a 6-member nitrogen-containingaromatic heterocyclic group, provided that at least one of L₂₁, L₂₂,L₂₃, L₂₄, L₂₅, and L₂₆ is ═N—, or —N(R₅₁)—; R₅₁ is a hydrogen atom or asubstituent, provided that at least one of Ar₅₁ and R₅₁ is a biarylgroup having a bonding axis capable of giving a internal rotationisomerism or a group having such a biaryl group, and the adjacentsubstituents may be condensed with each other to form a saturated orunsaturated ring.

(7) An electroluminescent material represented by the following FormulaD1,

wherein Ar₆₁ and Ar₆₂ are each an aryl group or an aromatic heterocyclicgroup; R₆₁ and R₆₂ are each a hydrogen atom or a substituent, providedthat at least one of Ar₆₁, Ar₆₂, R₆₁ and R₆₂ is a biaryl group having abonding axis capable of giving a internal rotational isomerism or agroup having such a biaryl group, and the adjacent substituents may becondensed with each other to form a saturated or unsaturated ring.

(8) An electroluminescent material represented by the following FormulaE1,M^(n′+)(L₇₁ ⁻)_(m)(R₇₁ ⁻)_(n′-m)  Formula E1wherein M is a metal atom capable of taking an ionized state of from 1-to 4-valent (i.e., giving 1- to 4-valent ions); n′ is a natural numberof from 1 to 4; L₇₁ ⁻ is a monovalent anion capable of forming an ionicbonding with M and having a portion capable of coordinating with M; m isa natural number of the same as n′ or less; R₇₁ ⁻ is a monovalent anioncapable of forming an ionic bond with M, provided that at least one ofL₇₁ ⁻ and R₇₁ ⁻ is a group having a moiety of biaryl group having abonding axis capable of giving an internal rotational isomerism.

(9) An electroluminescent material represented by the following FormulaF1 or F2,

wherein Z₁ and Z₂ are each independently a monovalent residue of a lightemitting compound; Z₃ is a k-valent residue of a light emittingcompound; k is a natural number of from 1 to 8, x is a natural number offrom 1 to 3; y is an integer of from 0 to 3, provided that plural groupsrepresented by Z₁ may be the same or different when x is 2 or more,plural groups represented by Z₂ may be the same or different when y is 2or more, and groups represented by Z₁ and Z₂ may be the same ordifferent when both of x and y are each 1 or more; R₈₁ and R₈₂ are eachindependently a substituent, n is an integer of from 0 to 4, m is aninteger of from 0 to 4, provided that plural groups represented by R₈₁may be the same or different and may be condensed with each other toform a ring when n is 2 or more, plural groups represented by R₈₂ may bethe same or different and may be condensed with each other to form aring when m is 2 or more, and R₈₁ and R₈₂ may be the same or differentwhen both of n and m are 1 or more. The substituent of each of Z₁, Z₂,R₈₁ and R₈₂ may form a condensed ring with the naphthalene ring.

(10) An electroluminescent material which is prepared using a4-halo-1,1′-binaphthyl derivative represented by Formula G1 as rawmaterial and has a monovalent biaryl group represented by Formula G2 inthe molecule of the material:

wherein X₉₁ is a halogen atom; R₉₁ and R₉₂ are each a substituent; n isan integer of 0 to 4; and m is an integer of 0 to 4, provided that whenn is 2 or more, plural R₉₁s may be the same or different, or condensedwith each other, when m is 2 or more, plural R₉₂s may be the same ordifferent, or condensed with each other, and when n and m are both 1 ormore, R₉₁ and R₉₂ may be the same or different.

(11) An electroluminescent element comprising an electroluminescentmaterial and an inorganic fluorescent substance which absorbs lightemitted from the electroluminescent material and fluoresces at themaximum emission wavelength different from that of light emitted fromthe electroluminescent material.

(12) The electroluminescent element described in (11), wherein theinorganic fluorescent substance is an inorganic fluorescent substanceprepared by a Sol-Gel method.

(13) The electroluminescent element described in (11) or (12), in whichthe inorganic fluorescent substance emits light having the maximumemission wavelength of from 400 nm to 700 nm.

(14) The electroluminescent element described in any one of from (11) to(13), wherein at least one of the inorganic fluorescent substance emitslight having the maximum fluorescence wavelength of from 600 nm to 700nm.

(15) An electroluminescent element which comprises an electroluminescentmaterial and a rare earth metal complex fluorescent substance whichabsorbs light emitted from the electroluminescent material andfluoresces at the maximum wavelength different from that of the lightemitted from the electroluminescent material.

(16) The electroluminescent element described in (15), wherein themaximum emission wavelength of light emitted from the rare-earth metalcomplex fluorescent substance is within the range of from 400 nm to 700nm.

(17) The electroluminescent element described in (15) or (16), whereinthe maximum emission wavelength of light emitted from the rare-earthmetal complex fluorescent substance is within the range of from 600 nmto 700 nm.

(18) The electroluminescent element described in any one of (11) to(17), wherein the maximum emission wavelength of light emitted from theelectroluminescent material is not more than 430 nm.

(19) The electroluminescent element described in (18), wherein themaximum emission wavelength of light emitted from the electroluminescentmaterial is within the range of from 400 nm to 430 nm.

(20) The electroluminescent element described in any one of (11) to(19), wherein the electroluminescent material is an organic LEDmaterial.

(21) The electroluminescent element described in any one of (11) to (19)wherein the electroluminescent material is an inorganic LED material.

(22) The electroluminescent element described in any one of (11) to(21), wherein the electroluminescent material is a compound selectedfrom the group consisting of compounds represented by Formula N1, A1,A2, A3, B1, C1, D1, E1, F1 or F2, as described in (1) to (9) or acompound as described in (10).

(23) An electroluminescent element comprising a substrate, providedthereon, a layer containing at least an electroluminescent material anda color conversion layer, wherein the color conversion layer contains aninorganic fluorescent substance which absorbs light emitted from theelectroluminescent material and emits light having the maximum emissionwavelength of from 400 nm to 500 nm, an inorganic fluorescent substanceemits light having the maximum emission wavelength of from 501 nm to 600nm, and an inorganic fluorescent substance emits light having themaximum emission wavelength of from 601 nm to 700 nm.

(24) An electroluminescent element comprising a substrate, providedthereon, a layer containing an electroluminescent material and a colorconversion layer, wherein the color conversion layer contains a rareearth metal complex fluorescent substance which absorbs light emittedfrom the electroluminescent material and emits light having the maximumemission wavelength of from 400 nm to 500 nm, a rare earth metal complexfluorescent substance emits light having the maximum emission wavelengthof from 501 nm to 600 nm, and a rare earth metal complex fluorescentsubstance emits light having the maximum emission wavelength of from 601nm to 700 nm.

(25) A color conversion filter which contains at least an inorganicfluorescent substance which absorbs light emitted from anelectroluminescent material and emits light having the maximum emissionwavelength of from 400 nm to 700 nm.

(26) A color conversion filter which contains an inorganic fluorescentsubstance which absorbs light emitted from an electroluminescentmaterial and emits light having the maximum emission wavelength of from400 nm to 500 nm, an inorganic fluorescent substance emitting lighthaving the maximum emission wavelength of from 501 nm to 600 nm, and aninorganic fluorescent substance emitting light having the maximumemission wavelength of from 601 nm to 700 nm.

(27) The color conversion filter described in (24) or (25) wherein atleast one of the inorganic fluorescent substance is one prepared by aSol-Gel method.

(28) A color conversion filter which contains at least an rare earthmetal complex fluorescent substance which absorbs light emitted from anelectroluminescent material and emits light having the maximum emissionwavelength of from 400 nm to 700 nm.

(29) A color conversion filter which contains a rare earth metal complexfluorescent substance which absorbs light emitted from anelectroluminescent material and emits light having the maximum emissionwavelength of from 400 nm to 500 nm, a rare earth metal complexfluorescent substance emitting light having the maximum emissionwavelength of from 501 nm to 600 nm, and a rare earth metal complexfluorescent substance emitting light having the maximum emissionwavelength of from 601 nm to 700 nm.

(30) A color conversion method, comprising conversion of a light in awavelength region shorter than a red light to the red light using aninorganic fluorescent substance which has been prepared by a sol-gelmethod.

(31) A color conversion method, comprising conversion of a light in awavelength region shorter than a red light to the red light using a rareearth metal fluorescent substance.

(32) The color conversion method described in (31), wherein the rareearth metal complex has the maximum absorption wavelength of not lessthan 340 nm.

(33) A rare earth metal complex fluorescent substance containing atleast an anionic ligand represented by the following formula R2:

wherein R₁₀₁ is a hydrogen atom or a substituent; Y₁₀₁ is an oxygenatom, a sulfur atom or —N(R₁₀₂), in which R₁₀₂ is a hydrogen atom or asubstituent; Z₁₀₁ is a group of atoms necessary to form a 4- to8-membered ring together with a carbon-carbon double bond.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates a cross sectional view of the structure of anelectroluminescent element.

DETAILED DESCRIPTION OF THE INVENTION

In the invention, the electroluminescent material is a material whichemits light by applying an electric field. In concrete, it is a materialwhich emits light when a positive hole injected from a anode and anelectron injected from a cathode are recombined, and is different from amaterial emitting light by collision energy of an accelerated electron(so-called inorganic electroluminescence). Thus, the electroluminescentmaterial relating to the invention includes materials of the (1) and (2)afore-mentioned and does not include those of the afore-mentioned (3)

The light emission by the electric field is a light emission of anelectroluminescent material when an electric current is applied to theelectroluminescent material contained in a light emission layer througha pair of electrodes arranged on both sides of a light emission layerlight emission layer so as to be faced to each other through the lightemission layer. It is considered that such the light-emission isoccurred by the following mechanism; the energy level of theelectroluminescent material is excited by recombination of an electroninjected from one of the electrodes and a positive hole injected fromthe other electrode in the light-emission layer, and the energy isemitted in a form of light when the energy level of the excitedelectroluminescent material is restored to the fundamental state.

Materials capable of emitting light by an electric field are usable inthe invention without any limitation, for example, both of an inorganicelectroluminescent material or inorganic LED such as gallium nitride GaNand an organic electroluminescent material or organic LED may be used.The organic LED is preferred from the view point of the light emissionefficiency.

In the invention, the electroluminescent material is preferably onewhich emits light having the maximum emission wavelength of 340 nm orless, more preferably from 400 nm to 430 nm, by the electric field.

Specifically, in the CIE chromaticity coordinates are preferred theregion corresponding to Purplish Blue, Bluish Purple and Purple, asshown in FIG. 4.16 “Relationship of Color Name of Color stimulus (colorof light) and Chromaticity Coordinates” of “Shikisaikagaku Handbook”(Handbook of Color Science), Fourth edition (edited by Nihon ShikisaiGakkai), page 105.

The electroluminescent material preferably usable in the invention isdescribed in concrete below.

The electroluminescent material preferably usable in the inventionincludes compounds represented by the foregoing Formula N1, A1, B1, C1,D1, E1, F1 or F2.

In Formulas N1, A1, B1, C1 and D1, the aryl group represented by Ar,Ar₁₁, Ar₁₂, Ar₁₃, Ar₄₁, Ar₄₂, Ar₅₁, Ar₆₁ or Ar₆₂ may be any one withoutany limitation as long as the number of π-electron thereof is 4n+2 inwhich n is a natural number, and it may be a single ring or condensedring. The aryl group may be substituted with a substituent such as analkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, anaryl group, a heterocyclic group, an amino group, a halogen atom, ahydroxyl group, a mercapto group, a carboxyl group, an acylamino group,a sulfonamido group, a phopsphonamido group, a carbamoyl group, an estergroup, an alkoxyl group, an aryloxyl group, a nitro group, a cyano groupand a silyl group. When plural substituents are substituted at adjacentpositions of the aryl group, the substituents may be condensed with eachother to form a carbon hydride ring or a heterocyclic ring, a moietyhaving a spiro structure may be further contained.

In Formulas N1, A1, B1, C1 and D1, the aromatic heterocyclic grouprepresented by Ar, Ar₁₁, Ar₁₂, Ar₁₃, Ar₄₁, Ar₄₂, Ar₅₁, Ar₆₁ or Ar₆₂ is aresidue formed by removing one hydrogen atoms from an optional positionof a single or condensed ring heterocyclic compound having a number ofπ-electron of 4n+2 in which n is a natural number. Examples of such theheterocyclic compound include furan, thiophene, pyrrol, imidazole,pyrazole, 1,2,4-triazole, 1,2,3-triazole, oxazole, thiazole, isooxazole,isothiazole, furazane, pyridine, pyrazine, pyrimidine, pyridazine and1,3,5-triazine, these heterocyclic ring each may further form acondensed ring.

In Formulas B1, C1, D1, E1, F1 and F2, the substituent represented byR₄₁, R₅₁, R₆₁, R₇₁, R₈₁, R₈₂, R₉₁, R₉₂, R₁₀₁, and R₁₀₂ may be a groupcapable of substituting without any limitation. Typical examples of thesubstituent include an alkyl group, a cycloalkyl group, an alkenylgroup, an alkynyl group, a heterocyclic group, an amino group, a halogenatom, a hydroxyl group, a mercapto group, a carboxyl group, an acylaminogroup, a sulfonamido group, a phosphonamido group, a carbamoyl group, anester group, an alkoxyl group, an aryloxyl group, a nitro group, a cyanogroup and a silyl group.

When plural substituents are substituted at adjacent positions of thearyl group, the substituents may be condensed with each other to form acarbon hydride ring or a heterocyclic ring, a moiety having a spirostructure may be further contained.

In Formula N1, the nitrogen-containing heterocyclic group represented by

is preferably a 5- or 6-member 6π-type aromatic heterocyclic ring suchas a 2-pyridyl group, a 2-pyrimidyl group, a 6-pyrimidyl group, a2-pyradyl group, a 3-pyridazyl group, a 2-oxazolyl group, a 2-thiazolylgroup, a 3-isooxazolyl group, a 3-isothiazolyl group, a 3-furazanylgroup, a 3-pyrazolyl group, a 2-imidazolyl group, a 4-imidazolyl group,a 2-pyrrolo group, a 2-oxadiazolyl group, a 2-thiadiazolyl group, a2-(1,2,4-triazyl) group, a 2-(1,3,5-triazyl) group and a3-(1,2,4-triazyl) group. The nitrogen-containing heterocyclic group maybe substituted with a substituent such as those described regarding R₄₁.The nitrogen-containing heterocyclic group may form a condensed ring,such as a 6-(1H-pyrazolo[5,1-c][1,2,4]triazolyl) group which is formedby condensing 2-quinolyl or 3-pyrazolyl ring, which are the condensingproduct of a 2-pyridyl group and a carbon hydride ring, with aheterocyclic ring.

In Formula N1, the aromatic hydrocarbon ring represented by

is a group formed by removing one hydrogen atom from an optionalposition of a 4n-2π type aromatic carbon hydride compound. Concreteexamples of the aromatic carbon hydride group include a phenyl group, a1-naphthyl phenyl group, a 2-naphthyl phenyl group, a 9-antholyl group,a 1-antholyl group, a 9-phenantholyl group, a 2-triphenylenyl group anda 3-peryrenyl group. The carbon hydride group may be substituted with asubstituent such as those described regarding R₄₁. The carbon hydridegroup may form a condensed ring such as a 9-pyrenyl group and a8-quinolyl group each formed by condensation of the carbon hydride ringwith 9-phenantholyl group and condensation of a phenyl group with aheterocyclic group, respectively.

In Formula N1, the aromatic heterocyclic group represented by

may be a aromatic heterocyclic group without any limitation as long asthe group is a 4n+2π type group and the atoms adjacent to the carbonatoms bonded with the nitrogen-containing aromatic heterocyclic groupare carbon atoms. Exemplary examples of the aromatic heterocyclic groupinclude a 3-pyridyl group, a 5-pyrimidyl group, a, 4-pyridazyl group, a5-pyridazyl group, a 4-isooxazolyl group, a 4-isothiazolyl group, a4-pyrazolyl group, a 3-pyrrolo group, a 3-furyl group and a 3-ethinylgroup. The aromatic heterocyclic group may be substituted with asubstituent such as those described regarding R₄₁, and may form acondensed ring.

In Formulas A1, B1, C1, D1, E1, F1 and F2, “a bonding axis capable ofgiving the internal rotation isomerism” is a bonding axis which cannotfreely rotate for 360° by the steric hindrance under an ordinarytemperature and pressure, such as the axis bonding the naphthalenenuclei in the following 1,1′-binaphthyl. Practically, a bonding axiscannot be rotated in a CPK-model is the “bonding axis capable of givingthe internal rotation isomerism”.

There is an isomer in the compound having the bonding axis capable ofgiving the internal rotation isomerism. Such the isomer is termed anatrop isomer or an internal rotation optical isomer, c.f. KagakuDaijiten vol. 6, p. 588. In another word, the compound or substituenthaving the axis capable of giving the internal rotation isomerism can bedefined as a compound or substituent having an atrop isomer or internalrotation optical isomer.

Although an example of the basic skeleton structure of the substituenthaving a biaryl group which has the axis capable of giving the internalrotation isomerism is shown in the followings, the invention is notlimited to this example. The substituent is formed by removing onehydrogen atom from the compound shown below. The basic skeletonstructure may be substituted with a substituent those describedregarding R₄₁, and may form a condensed ring.

In the formulas, substituents represented by R₁₀₁ to R₁₃₇ are thosewhich have a Taft's stereo-parameter of not more than −1.00, including abromone atom, iodine atom, straight-chained alkyl group such as methyl,ethyl, or propyl, a branched alkyl group such as isopropyl or t-butyl,cyclic alkyl such as cyclopentyl or cyclobutyl, an aromatic hydrocarbongroup such as phenyl or naphthyl, heterocyclic group such as pydidyl,imidazolyl or furyl, nitro and mercapto group. The Taft'sstereo-parameter is referred to S. H. Unger, Phys. Org. Chem. 12, 91(1976) and “Yakubutsu no Kozokassei-sokan” (Kagaku no Ryoiki Zokan No.122, published by Nankodo), pages 124-126.

In Formula A3, the aryl group having a 1,1′-binaphthyl moiety, which isrepresented by Ar₂₁, Ar₂₂ or Ar₂₃ is:

-   (1) a binaphthyl group, i.e., one in which hydrogen is removed from    an arbitrary position of the 11′-binaphthyl,-   (2) a substituted 1,1′-binaphthyl group, in which one hydrogen atom    is removed and substituent(s) are substituted for arbitrary m    hydrogen atoms are removed, and-   (3) an aryl group substituted by the above described 1,1′-binaphthyl    group.    Examples thereof include:

In Formula E1, the metal element represented by M may be ones capable oftaking an ion structure of from 1- to 4-valent without any limitation.The metal element is preferably Be, Mg, Ca, Sr, Ba, Zn, Cd, Hg, Pd, Cu,B, Al, Ga, In, Tl, Si and Ga, more preferably Be, Mg, Ca, Sr, Ba, Zn,Cu, B, Al, Ga and In, and most preferably Be, Al, Zn and Ga.

In Formula E1, the monovalent anion represented by L₇₁ ⁻, which forms anion bonding with M and has a portion capable of coordinating with M, isone capable of taking a state under an acidic condition in which aproton is added to an oxygen atom, a sulfur atom or a nitrogen atom, inanother word, one capable of taking a state formed by removing a protonfrom a compound having a dissociable group such as —OH, —NH or —SH, andthe anion also has an atom capable of coordinating with a metal such asa nitrogen atom and a chalcogen atom (O, S, Se, Te) at a position away 2or 3 atoms from the oxygen atom, the sulfur atom or the nitrogen atom.Examples of such the anion include an oxygen anion formed by removing aproton from the hydroxyl group of 8-hydroxyquinoline and a nitrogenanion formed by removing a proton from the NH at position-1 of1H-2-(1-pyrazolyl)imidazole.

In Formula E1, the monovalent anion capable of forming an ionic bondwith M represented by R₇₁ ⁻ may be one capable of forming an anion undera basic condition of pH of 8 or less, such as an anion formed byremoving a proton from 4-hydroxy-1,1′-biphenyl, 2-mercaptonaphthalene or1H-pyrazolo[5,1-c][1,2,4]triazole.

In Formula F1, the monovalent light emitting compound residuerepresented by Z₁ or Z₂ is one formed by removing a hydrogen atom or asubstituent from an optional portion of a compound which emits light atan ordinary temperature. In Formula F2, the k-valent light emittingcompound residue represented by Z₃ is one formed by removing k atoms ofhydrogen or k substituents from an optional portion of a compound whichemits light at an ordinary temperature. The light emission of the lightemitting compound under an ordinary temperature may be fluorescence orphosphorescence.

The light emitting compound capable of forming the light-emittingcompound residue includes a fluorescent dye having a absorption band inthe visible region such as a laser dye, a fluorescent compound having aabsorption band in the ultraviolet region such as a fluorescentwhitening agent, and a phosphorescent substance such as a platinumcomplex of porphyrin and biacetyl. In concrete, the organic fluorescentsubstances described in Kunio Yagi, Zenichi Yoshida, Riichi Oota,“Keikou-Riron•Sokutei•Ouyou”(Fluorescence—Theory•Determination•Application—), p.p. 99-122, Nankodo,the fluorescent whitening agent described in ibid., p.p. 251-270, andthe fluorescent dyes described in ibid., p.p. 274-287. The followingsare particularly preferable; a condensed aromatic carbon hydride cycliccompound such as triphenylene and perylene, a linear conjugatemulti-ring carbon hydride compound such as p-terphenyl and quaterphenyl,a condensed aromatic heterocyclic compound such as acrydine, quinoline,carbazole, carbazone, fluorene, xanthione, aroxazine, acrydone,furabone, coumarin, naphthoimidazole, benzoxazole and dibenzophenazine,an aromatic heterocyclic compound such as thiazole, oxazole, oxadiazole,thiadiazole and triazole, a conjugate aliphatic compound such asaminochloromaleic amide, methylaminocitraconic methylimide, decapentaenecarboxylic acid and decapentaene dicarboxylic acid, A fluorescent dyesuch as Acrydine Orange NO, Methylene Blue, Fluorescein, Eosine,Rhodamine and Benzoflabine, a light sensitive dye compound such asoxacarbocyanine, carbocyanine, thiacarbocyanine and2-(anilinopolyethynyl)-benzothiazole, a natural dye compound such asporphiline, chlorophile and liboflabine, and a fluorescent whiteningagent such as diaminostilbene type, distyrylbenzene type, benzidinetype, diaminocarbazole type, triazole type, imidazole type, oxazoletype, imidazolone type, dihydropyridine type, coumarine type,carbostyryl type, diaminodibenzothiophene oxide type, diaminofluorenetype, oxacyanine type, aminonaphthalimide type, pyrazoline type andoxazole type. These compounds each may have a substituent and may form acondensed ring.

Although concrete examples of electroluminescent material of theinvention are shown below, the electroluminescent material usable in theinvention is not limited thereto.

The electroluminescent element in the invention is an element comprisesa substrate, provided thereon, the foregoing electroluminescent materialand an inorganic fluorescent substance or a rare-earth metal complexfluorescent substance which absorbs light emitted from theelectroluminescent material and fluoresces light, and a pare ofelectrodes arranged so as to be faced to each other through the layercontaining the electroluminescent material. The electroluminescentmaterial and the inorganic fluorescent substance or the rare-earth metalcomplex fluorescent substance are separately contained in differentlayers, and are not contained in the same layer. The electroluminescentmaterial used in the invention may be an emission material, ahole-injection material or an electron-injection material, and theemission material is preferred. The emission material may havecapabilities of hole-injection and electron-injection in combination. Incases where the electroluminescent material used in the invention isemployed as an emission material, a doping material (also called adopant or guest) may be optionally employed for the electroluminescentmaterial used as a host. In the followings, the electroluminescentmaterial is present in any one of the emission layer, hole-injectionlayer and electron-injection layer; and the inorganic and/or rare-earthmetal complex fluorescent substance are present in the color conversionlayer. An electron injection layer or a positive hole injection layermay be provided in the electroluminescent element of the inventionaccording to necessity.

Substrates used in the electroluminescent element used in the inventionare not specifically limited so far as they are transparent, such asglass and plastic resins. Typical examples of the material usable as thesubstrate of the electroluminescent element according to the inventioninclude glass, quartz, and an optically transparent plastic film eventhough any material can be used without any limitation as long as thematerial is transparent. Examples of the transparent plastic filminclude a film of polyethylene terephthalate (PET), polyethylenenaphthalate (PEN), polyethersulfon (PES), polyetherimide,polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide,polycarbonate (PC), cellulose triacetate (TAC), and celluloseacetate-propionate.

In the electroluminescent element, the electroluminescent materialaccording to the invention is preferably contained in the emissionlayer. Commonly known emission material may be used. Examples thereofinclude low molecular type emission material described in “Yuki-EL-Soshito Kogyoka-saizensen” (published N.T.S. Co. Ltd, 1998, hereinafter,denoted Reference A), Sect. 1, Chapter 3, page 35-51; dye dopingmaterials described in the reference A, Sect. 1, Chapter 4, pages 55-79;and high molecular type materials described in the reference A, Sect. 1,Chapter 5, pages 81-100.

The electroluminescent element is usually constituted by a single orplural layers which are sandwiched between two electrodes. Theconstituting layers include, additionally to the light emission layer, apositive hole injection layer which is also referred to a chargeinjection layer, a hole injection layer, a charge transportation layeror a hole transportation layer, and an electron injection layer which isalso referred to an electron transportation layer.

The positive hole injection layer and the electron injection layer eachmay have a multi-layered structure, for example the following layerstructure may be taken: Anode/1st positive hole injection layer/2ndpositive hole injection layer (positive hole transportation layer)/Lightemission layer/2nd electron injection layer (electron transportationlayer) 1st electron injection layer/Cathode

Examples of layer structure of the electroluminescent element of theinvention are shown below. In the followings, the positive holeinjection layer and the electron injection layer each may be a layercomposed of laminated layers of plural compound as above-mentioned eventhough description regarding the plural laminated positive holeinjection layers and/or the plural laminated electron injection layersare omitted.

-   (i) Substrate/Color conversion layer/Substrate/Anode/Light emission    layer/Cathode-   (ii) Substrate/Color conversion layer/Substrate/Anode/Positive hole    injection layer/Light emission layer/Cathode-   (iii) Substrate/Color conversion layer/Substrate/Anode/Light    emission layer/Electron injection layer/Cathode-   (iv) Substrate/Color conversion layer/Substrate/Anode/Positive hole    injection layer/Light emission layer/Electron injection    layer/Cathode-   (v) Substrate/Anode/light emission layer/Cathode/Color conversion    layer/Substrate-   (vi) Substrate/Anode/Positive hole injection layer/Light emission    layer/Cathode/Cover conversion layer/Substrate-   (vii) Substrate/Anode/Light emission layer/Electron injection    layer/Cathode/Color conversion layer/Substrate-   (viii) Substrate/Anode/Positive hole injection layer/Light emission    Layer/Electron injection layer/Cathode/Color conversion    layer/Substrate

In the above-mentioned, the substrate contacting with the colorconversion layer and that contacting with the anode may be the same ordifferent. Outside of the element may be covered with the substrate.

A buffer layer (electrode interface layer) may be arranged between theanode and the light emission layer or the positive hole injection layer,and between the cathode and the light emission layer or the electroninjection layer.

The buffer layer is a layer provided between the electrode and theorganic compound layer for lowering the driving voltage or raising thelight emission efficiency, which are described in Vol. 2, Section 2,p.p. 123-166 of Publication A. The buffer layer includes an anode bufferlayer and a cathode buffer layer.

Examples of the anode buffer layer include a phthalocyanine buffer layertypically comprising copper phthalocyanine, an oxide buffer layertypically comprising vanadium oxide, an amorphous carbon buffer layerand a polymer buffer layer comprising an electroconductive polymer suchas polyaniline (Emeraldine) and polythiophene.

Examples of the cathode layer buffer include a metal cathode buffertypically comprising a metal strontium and aluminum, an alkali metalcompound buffer layer typically comprising lithium fluoride, analkali-earth metal compound buffer layer typically comprising magnesiumfluoride and an oxide buffer layer typically comprising aluminum oxide.

The buffer layer is desirably a extremely thin layer and the thicknessthereof is preferably from 0.1 to 100 nm depending on the material.

The emission layer, hole-injection layer, electron-injection layer andbuffer layer can be prepared as a thin layer by a known method such as aevaporation method, a spin-coat method, a casting method and a LBmethod. The layer is preferably a sedimented molecule layer. Thesedimented molecule layer is a thin layer formed by sedimentation of thecompound from a gas phase or a layer formed by solidifying from themolten or liquid phase of the compound. The sedimented molecule layercan be distinguished from a thin layer formed by the LB method(cumulative molecule layer) based on the difference in the coagulationstructure and the high dimensional structure, and in the functionaldifference thereof caused by the structural difference.

Moreover, the light emission layer can be formed by the method such asthat described in JP O.P.I. No. 57-51781, by which the light emissionmaterial is dissolved in a solvent together with a binder such as aresin, and thus obtained solution is formed into a thin layer by amethod such as spin-coat method. It is preferred that the thickness iswithin the range of from 5 nm to 5 μm, although the thickness of thelayer thus formed may be optionally selected according to necessitywithout any limitation.

For the anode of the electroluminescent element, a metal, an alloy andan electroconductive compound each having a high working function of notless than 4 eV, and mixture thereof are preferably used as the electrodematerial. Concrete examples of such the electrode material include ametal such as Au, and a transparent electroconductive material such asCuI, indium oxide (ITO), SnO₂, ZnO and Zn-doped indium oxide (IZO). Theanode may be prepared by evaporating or spattering such the electrodematerial to form a thin layer, and forming the layer into a desired formby a photolithographic method. When required precision of the pattern isnot so high (not less than 100 mm), the pattern may be formed byevaporating or spattering through a mask having a desired form.

When light is output through the anode, it is desired that thetransparence of the anode is 10% or more, and the sheet resistivity ofthe anode is preferably not more than 10³Ω/□. It is preferably withinthe range of from approximately 10 nm to 1 μm, more preferably from 10to 200 nm, although the thickness of the anode may be optionallyselected.

On the other hand, for the cathode, a metal (also referred to anelectron injection metal), an alloy, and an electroconductive compoundeach having a low working function (not more than 4 eV), and a mixturethereof are used as the material of electrode. Concrete examples of suchthe electrode material include sodium, potassium, sodium-potassiumalloy, magnesium, lithium, a magnesium/copper mixture, amagnesium/silver mixture, a magnesium/aluminum mixture, magnesium/indiummixture, a aluminum/aluminum oxide (Al₂O₃) mixture, indium, alithium/aluminum mixture and a rare-earth metal.

Among then, a mixture of an electron injection metal and a metal higherin the working function than that of the electron injection metal, suchas the magnesium/silver mixture, magnesium/aluminum mixture,magnesium/indium mixture, aluminum/aluminum oxide (Al₂O₃) andlithium/aluminum mixture, is suitable from the view point of theelectron injection ability and the resistivity to oxidation.

However, the limitation of the working function is released when thecathode buffer layer is coated on the surface of the cathode. Forexample, such described as in JP O.P.I. No. 11-224783, a material havinga high working function such as ITO, SnO₂, In₂O₃ and ZnO:Al can be usedas the cathode which are usually used a the cathode when a fluoride ofan alkali metal or an alkali-earth metal is used as the cathode bufferlayer (in the publication described as an electron injection layer).Moreover, it has been known that aluminum can be used as the cathodematerial when lithium fluoride is used as the cathode buffer layer(thickness: 0.5 to 1 μm) as described in Publication (A), page 145,lines 15-28. When such the cathode material is used, an element definedas “metal” in the Periodical Table such as silver, copper, platinum andgold is usable additionally to the above-mentioned metal oxides andaluminum.

The cathode can be prepared by making such the material to a thin layerby a method such as an evaporation or spattering method.

Moreover, it may be formed by a plating method such as described in JPO.P.I. No. 11-8074.

The sheet resistivity of the cathode is preferably not more than 10³Ω/γ, and the thickness of the cathode is preferably from 10 nm to 1 μm,more preferably from 50 to 2,000 nm.

It is preferable for raising the light emission efficiency that theelectrode arranged between the light emission layer and the colorconversion layer is transparent or semi-transparent so as to permeatelight therethrough. Herein, the expression, the electrode beingtransparent or semi-transparent means that the transmittance of thetotal visible region of 400 to 700 nm is 20% or more, and preferably 50%or more.

In the invention, a positive hole injection layer may be providedaccording to necessity. The positive hole injection layer has a functionof transporting the positive hole injected from the anode to the lightemission layer. Many positive holes can be injected in a loweredelectric field by the presence of the positive hole injection layerbetween the anode and the light emission layer. Moreover, the lightemission ability of the element is made excellent by raising the lightemission efficiency since the electrons injected into the light emissionlayer from the cathode or the electron injection layer are accumulatedat the interface in the light emission layer by a barrier to electronexisting at the interface between the light emission layer and thepositive hole injection layer.

The material to be used for the positive hole injection layer(hereinafter referred to a positive hole injection material) can beoptionally selected from known materials without any limitation.

The positive hole injection material may be either an organic substanceor an inorganic substance as long as it has a positive hole injectionability or an ability to form a barrier to electron.

Various kinds of organic compounds, for example, those described in JPO.P.I. Nos. 63-295695, 2-191694, 3-792, 5-234681, 5-239455, 5-299174,7-126225, 7-126226, 8-100172 and EP No. 0650955 A1, can be used as thepositive injection hole material. Examples of them include aphthalocyanine derivative, a tetraarylbenzidine compound, an aromatictertiary amine, a hydrazone derivative, a carbazole derivative, atriazole derivative, an imidazole derivative an oxadiazole derivativehaving an amino group and polythiophene. These compounds may be used incombination of two or more. When the compounds are used in combination,they may be formed in a separated layers or mixed with together.

When the positive hole injection layer is formed by lamination (in thecase of the functions of positive hole injection and positive holetransportation are separately allocated), a preferable combination canbe selected from these materials. In such the case, it is preferable tolaminate the compounds in the order of small ionized potential from theanode such as ITO. The compound having a high thin film forming abilityis preferably used such as the starburst type compounds described in JPO.P.I. No. 4-308688.

Typical examples of the aromatic tertiary amine compound includeN,N,N′,N′-tetraphenyl-4,4′-diaminophenyl,N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4,-diamine(TPD), 2,2′-bis(4-di-p-tolylaminophenyl)propane,1,1′-bis(4-di-p-tolylaminophenyl)cyclohexane,N,N,N′,N′-tetra-p-tolyl-4,4′-diaminobiphenyl,1,1′-bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane,bis(4-dimethylamino-2-methylphenyl)-phenylmethane,bis(4-di-p-tolylaminophenyl)phenylmethane,N,N′-diphenyl-N,N′-di(4-methoxyphenyl)-4,4′-diaminobiphenyl,N,N,N′,N′-tetraphenyl-4,4′-diaminodiphenylether,4,4′-bis(diphenylamino)quaterphenyl, N,N,N-tri(p-tolyl)amine,4-(di-p-tolylamino)-4′-[4-(di-p-tolylamino)styryl]stilbene,4-N,N-diphenylamino-(2-diphenylvinyl)benzene, N-phenylcarbazole,compounds described in U.S. Pat. No. 5,061,569 which have two condensedaromatic rings in the molecule thereof such as4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD), and compoundsdescribed in JP O.P.I. No. 4-308688 such as4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]-triphenylamine (MTDATA)in which three triphenylamine units are bonded in a starburst form.

As the inorganic positive hole injection material, p-Si and p-SiC areusable.

The positive hole injection layer can be formed by making the positivehole injection material to a thin layer by a known method such as avacuum evaporation method, a spin coat method a casting method and a LBmethod. The thickness of the positive hole injection layer is preferablyapproximately from 5 nm to 5 μm even though there is no specificlimitation thereon.

The electron injection layer which is provided according to necessity isa layer having a function of transporting electrons injected to thecathode to the light emission layer. The material of the electroninjection layer may be optionally selected from known compounds.

The electron injection layer has a function of to easily inject electronfrom the cathode, a function of to transport electron and to inhibitpositive hole, and is provided when a compound having a relatively lowelectron transportation is used in the light emission layer.

The electron injection layer may be separated into a layer having theelectron injection ability and a layer having a electron transportationability.

Examples of the material of the electron injection layer (hereinafterreferred to electron injection material) include a nitro-substitutedfluorene derivative, a diphenylcuinone derivative, a thiopyrane dioxidederivative, a heterocyclic tetracroxylic acid anhydride such asnaphthaleneperylene, a carbodiimide, a fluolenylidenemethane derivative,an anthraquinodimethane and anthorone derivative, and a oxadiazolederivative. It is found by the inventors that a series of electrontransmission compounds described in JP O.P.I. No. 59-194393 can be usedas the electron injection material even though the compounds aredescribed in the publication as the material for making the lightemission layer. Moreover, a thiadiazole derivative which is formed bysubstituting the oxygen atom in the oxadiazole ring of the foregoingoxadiazole derivative by a sulfur atom, arylamino- oralkylamino-substituted triazole derivatives and a quinoxaline derivativehaving a quinoxaline ring known as an electron withdrawing group areusable as the electron injection material.

A metal complex of 8-quinolynol derivative such as aluminumtris-(8-quinolynol) (Alq), aluminum tris-(5,7-dichloro-8-quinolynol),aluminum tris-(5,7-dibromo-8-quinolynol), aluminumtris-(2-methyl-8-quinolynol), aluminum tris-(5-methyl-8-quinolynol),zinc bis-(8-quinolynol) (Znq), and a metal complex formed by replacingthe, central metal of the foregoing complexes with another metal atomsuch as In, Mg, Cu, Ca, Sn, Ga or Pb, can be used as the electroninjection material. Furthermore, metal complex type materials describedin the reference A at pages 38-48, a metal free and metal-containingphthalocyanine, and a derivative thereof in which the terminal of eachof the compounds is replaced by a substituent such as an alkyl group ora sulfonic acid group are also preferably used as the electron injectionmaterial. An inorganic semiconductor such as n-Si and n-SiC may also beused as the electron injection material.

The electron injection layer can be formed by making the electroninjection material to a thin layer by a known method such as a vacuumevaporation method, a spin coat method a casting method and a LB method.The thickness of the positive hole injection layer is preferablyapproximately from 5 nm to 5 μm even though there is no specificlimitation thereon.

The electron injection layer may have a single layer structurecontaining one or more kinds of the electron injection material or amulti-layered structure composed of plural layers having the same ordifferent composition.

Next, the inorganic fluorescent substance and the rare-metal complexfluorescent substance relating to the invention are described below.

In the invention, a substance capable of absorbing light emitted fromthe electroluminescent material and emitting light different from thelight emitted from the electroluminescent material in the maximumemission wavelength thereof may be used as the inorganic fluorescentsubstance and the rare-metal complex fluorescent substance.

In the above-mentioned, the difference between the maximum emissionwavelength of the light emitted from the fluorescent substance and thatof the light emitted from the electroluminescent material is 10 nm ormore.

The inorganic fluorescent substance or the rare-earth metal fluorescentsubstance to be contained in the electroluminescent element according tothe invention is preferably one emitting fluorescent light having themaximum emission wavelength within the range of from 400 nm to 700 nm.

It is preferable that the inorganic fluorescent substance or therare-earth metal fluorescent substance to be contained in theelectroluminescent element according to the invention preferablycontains at least one capable of emitting light having the maximumemission wavelength larger by 180 nm or more than the maximum emissionwavelength of light emitted from the electroluminescent material.

It is preferable for full color displaying that the electroluminescentelement of the invention has a color conversion layer containing atleast one kind of the inorganic fluorescent substance or the rare-earthmetal fluorescent substance emitting light having the maximum emissionwavelength of from 400 nm to 500 nm, at least one kind of those emittinglight having the maximum emission wavelength of from 501 nm to 600 nmand at least one kind of those emitting light having the maximumemission wavelength of from 601 nm to 700 nm when absorbs the lightemitted from the electroluminescent material.

The color conversion layer may be take various forms according to theuse.

For example, when a flat white light emission display is prepared, amixture of a blue light emission fluorescent substance and a yellowlight emission fluorescent substance or a mixture of a blue, green andred light emission fluorescent substances. In such the case, thefluorescent substances may be uniformly coated without any pattern.

When a multi-color conversion filter such as a color filter for a liquiddisplay is required, a fluorescent substance emitting light havingrequired color is patterned in a form of stripe, dot or mosaic. Thepatterning can be carried out by the method usually applied forproducing usual color filter of liquid display. In concrete, the methodsuch as a pigment dispersion method, printing method and an ink-jetmethod may be applied.

Although there is no limitation on the inorganic fluorescent substanceor the rare-earth metal fluorescent substance to be used in theinvention, ones comprised of a combination of metal oxide such as YO₂S,Zn₂SiO₄ and Ca₅(PO₄)₃Cl, or a sulfide such as ZnS, SrS and CaS as themother crystal and an ion of rare-earth metal such as Ce, Pr, Nd, Pm,Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb or an ion of metal such as Ag, Al,Mn and Sb as an activator or a coactivator is preferred.

The metal oxide is preferable as the mother crystal, for example,aluminum oxide, silicon oxide, phosphate and halophosphate eachsubstituted with an alkali-earth metal such as (X)₃Al₁₆O₂₇, (X)₄Al₁₄O₂₅,(X)₃Al₂Si₂O₈, (X)₄Si₂O₈, (X)₂Si₂O₄, (X)₂P₂O₇, (X)₂P₂O₅, (X)₅(PO₄)Cl and(X)₂Si₃O₈-2(X)Cl₂ are cited as the typical mother crystal, wherein X isan alkali-earth metal and the alkali-earth metal may be single metalcomposition or a mixture of 2 or more kinds of the metal.

Preferable mother crystal other than those includes an oxide or sulfideof zinc, an oxide of a rare-earth metal such as yttrium, gadolinium andlanthanum, or one in which a part of the oxide atoms is replaced by asulfur atom, a sulfide of rare-earth metal and the oxide or the sulfideof such the rare-earth metal in which an optional metal element iscombined.

Preferable examples of the mother crystal are shown below; ZnS, Y₂O₂S,Y₃Al₅O₁₂, Y₃SiO₃, Zn₂SiO₄, Y₂O₃, BaMgAl₁₀O₁₇, BaAl₁₂O₁₉,(Ba,Sr,Mg)O.aAl₂O₃, (Y,Gd)BO₃, YO₃, (Zn,Cd)S, SrGa₂S₄, SrS, GaS, SnO₂,Ca₁₀(PO₄)₆(F,Cl)₂, (Ba,Sr)(Mg,Mn)Al₁₀O₁₇, (Sr,Ca,Ba,Mg)₁₀(PO₄))Cl₂,(La,Ce)PO₄, CeMgAl₁₁O₁₉, GdMgB₅O₁₀, Sr₂P₂O₇, Sr₄Al₁₄O₂₅, Y₂SO₄, Gd₂O₂S,Gd₂O₃, YVO₄ and Y(P,V)O₄.

A part of the element of the above-listed mother crystal, the activatorand the coactivator each may be replaced by an element of the same tribein the periodic table, and there is no limitation on the elementcomposition thereof as long as one capable of emitting visible light byabsorbing ultraviolet or violet region of light.

In the invention, an ion of lanthanoid element such as La, Eu, Tb, Ce,Yb and Pr, and an ion of metal such as Ag, Mn, Cu, In and Al ispreferred as the activator or coactivator of the inorganic fluorescentsubstance. The doping amount of the activator or the coactivator ispreferably from 0.001 to 100 mole-%, more preferably 0.01 to 50 mole-%of the mother crystal.

The activator and the coactivator are doped in the crystal by replacinga part of the ion constituting the mother crystal by the ion such as thelanthanoid ion. The exact composition of the crystal of the fluorescentsubstance can be described as follows. However, the value of x and y inthe following formulas are not described except in the case a specificnote is attached since the amount of the activator tends to no influenceon the fluorescent property of the substance. For example,Sr_(4-x)Al₁₄O₂₅:Eu²⁺ _(x) is described in Sr₄Al₁₄O₂₅:Eu²⁺.

Although examples of typical inorganic fluorescent substance composed ofthe mother crystal and the activator are described below, thefluorescent substance usable in the invention is not limited to them:(Ba_(z)Mg_(1-z))_(3-x-z)Al₁₆O₂₇:Eu²⁺ _(x), Mn²⁺ _(y),Sr_(4-x)Al₁₄O₂₅:Eu²⁺ _(x), (Sr_(1-z)Ba_(z))_(1-x)Al₂Si₂O₈:Eu²⁺ _(x),Ba_(2-x)SiO₄:Eu²⁺ _(x), Sr_(2-x)SiO₄:Eu²⁺ _(x), Mg_(2-x)SiO₄:Eu² _(x),(BaSr)_(1-x)SiO₄:Eu²⁺ _(x), Y_(2-x-y)SiO₅:Ce³⁺ _(x), Tb³⁺ _(y),Sr_(2-x)P₂O₅:Eu²⁺ _(x), Sr_(2-x)P₂O₇:Eu²⁺ _(x),(Ba_(y)Ca₂Mg_(1-y-z))_(5-x)(PO₄)₃ClEu²⁺ _(x) andSr_(2-x)Si₃O₈-2Srl_(2:Eu) ²⁺ _(x), in which x, y and z are each anoptional number.

Inorganic fluorescent substances preferably usable in the invention areshown below. However, the inorganic fluorescent substance usable in theinvention is not limited to these compound.

Blue Light-emissive Inorganic Fluorescent CompoundSr₂P₂O₇:Sn⁴⁺  (BL-1)Sr₄Al₁₄O₂₅:Eu²⁺  (BL-2)BaMgAl₁₀O₁₇:Eu²⁺  (BL-3)SrGa₂S₄:Ce³⁺  (BL-4)CaGa₂S₄:Ce³⁺  (BL-5)(Ba,Sr) (Mg,Mn)Al₁₀O₁₇:Eu²⁺  (BL-6)(Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu²⁺  (BL-7)BaAl₂SiO₈:Eu²⁺  (BL-8)

[Green Light-emissive Inorganic Fluorescent Compound](BaMg)Al₁₆O₂₇:Eu²⁺,Mn²⁺  (GL-1)Sr₄Al₁₄O₂₅:Eu²⁺  (GL-2)(SrBa)Al₂Si₂O₈:Eu²⁺  (GL-3)(BaMg)₂SiO₄:Eu²⁺  (GL-4)Y₂SiO₅:Ce³⁺,Tb³⁺  (GL-5)Sr₂P₂O₇—Sr₂B₂O₅:Eu²⁺  (GL-6)(BaCaMg)₅(PO₄)₃Cl:Eu²⁺  (GL-7)Sr₂Si₃O₈-2SrCl₂:Eu²⁺  (GL-8)Zr₂SiO₄,MgAl₁₁O₁₉:Ce³⁺,Tb³⁺  (GL-9)Ba₂SiO₄:Eu²⁺  (GL-10)Sr₂SiO₄:Eu²⁺  (GL-11)(BaSR)SiO₄:Eu²⁺  (GL-12)

[Red Light-emissive Inoroganic Fluorescent Compound]Y₂O₂S:Eu³⁺  (RL-1)YAlO₃:Eu³⁺  (RL-2)Ca₂Y₂(SiO₄)₆:Eu³⁺  (RL-3)LiY₉(SiO₄)₆O₂:Eu³⁺  (RL-4)YVO₄:Eu³⁺  (RL-5)CaS:Eu³⁺  (RL-6)

In the invention, an inorganic fluorescent substance prepared by abuildup method without mechanical crushing process in the productioncourse is preferably used for emitting high luminance light. Onesproduced by a liquid phase methods such as a Sol-Gel method areparticularly preferred. As to the composition thereof, ones having aninorganic oxide as the mother crystal are preferred.

The Sol-Gel synthesis method is a method in which the synthesisbasically started from a solution and the material is synthesized at atemperature lower than the melting point thereof through a sol and gelstates as described in detail in Sumio Sakka “Application of Sol-GelMethod” 1997, Agnes Shofuusha. The Sol-Gel method in the invention is amethod in which a reaction in a liquid phase is carried out in at leastone step thereof. Such the method can be established from the methodcarried out by a reaction in a molten state applied for producing anusual inorganic fluorescent substance. The production procedure bySol-Gel method is a method in which necessary amounts of elements to beused as the mother crystal, activator or coactivator in a form of metalalkoxide such as tetramethoxysilane Si(OCH₃)₄ andeuropium-2,4-pentanedionate Eu³⁺(CH₃COCH═C(OCH₃)₃, metal complex, doublealkoxide prepared by addition of an elemental metal to an organicsolvent solution of the above metal alkoxide or metal complex such asMg[Al(OBu)₃]₂ which is prepared by addition of metallic magnesium to a2-butanol solution of Al(OBu)₃, metal halide, organic acid salt of metalor elemental metal are mixed and thermally or chemically polymerized orcondensed. The product may be subjected to a baking or reducingtreatment according to necessity.

The Metal in the metal alkoxide, metal halide, metal salt and metal tobe used in the invention includes “metals” defined in the PeriodicalTable, all element of “transition metals”, all elements of actinoid andboron, carbon and silicon which are usually defined as “non metals”.

The inorganic fluorescent substance may be subjected to a surfaceproperty improving treatment. The method for such the treatment includesa chemical treatment by silane coupling agent, a physical treatment byan addition of fine particle having a size of submicron, and acombination thereof.

All compounds described in “Catalogue of NUC silicone silane couplingagent”, Aug. 2, 1997, published by Nihon Unicar Co., Ltd., are usable asthe silane coupling agent in the invention. Concrete examples of suchthe compound include β-(3,4-epoxycyclohexyl)ethyltrialkoxysilane,glycidyloxyethyltriethoxysilane,γ-acryloyloxy-n-propyl-tri-n-propyloxysilane,γ-methacryloyloxy-n-propyl-n-porpyloxysilane,di-(γ-acryloyloxy-n-propyl)-di-n-propyloxysilane,acryloyloxydimethoxyethylsilane,N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane,N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane,γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane andγ-mercaptopropyltrimethoxysilane.

The fine particle usable in the invention is preferably an inorganicfine particle such as silica, titania, zirconia and zinc oxide.

When the fluorescent substance is produced by the Sol-Gel method, aprocedure may be applied in which a precursory solution of thefluorescent substance or a solution containing a primary particle of thefluorescent substance is patterned on a transparent substrate by aprinting method or an ink-jet method and then the pattern is subjectedto a crystallizing treatment such as a baking or reduction treatment ora treatment for making a high luminance emission ability.

The rare-earth metal complex fluorescent substance usable in theinvention includes ones containing Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy,Ho, Er, Tm or Yb. The organic ligand composing the complex may be eitheran aromatic one or non aromatic one, and an aromatic organic ligandhaving a absorption in the region of not less than 250 nm is preferred.Compounds represented by the following Formula 1 or Formula R2 is morepreferable.Xa-(La)-(Lb)n-(Lc)-Ya  Formula 1

In the above formula, La, Lb and Lc are each independently an atomhaving 2 or more bonds, n is 0 or 1, Xa is a substituent having an atomcapable of coordinating at a position adjacent to La, and Ya is asubstituent having an atom capable of coordinating at a positionadjacent to Lc. An optional portion of Xa and La, or an optional portionof Ya and Lc, each may be bonded with together to form a ring. Moreover,at least one of an aromatic carbon hydride ring and an aromaticheterocyclic ring exists in the complex molecule, provided that thearomatic carbon hydride ring and the aromatic heterocyclic ring may beabsent when Xa-(La)-(Lb)n-(Lc)-Ya represents β-diketone derivatives,β-ketoester derivatives, β-ketoamide derivatives, crown ether in whichan oxygen atom of the above-described ketone is replaced by an optionalnumber of sulfur atoms or —N(R₁)— groups, an aza-crown ether, athia-crown ether or a crown ether in which an oxygen atom is replaced byan optional number of sulfur atoms or —N(R₁)— groups.

In Formula 1, the atom capable of coordinating represented by Xa or Yais preferably an oxygen atom, a nitrogen atom, a sulfur atom, a seleniumatom or a tellurium atom, and an oxygen atom, a nitrogen atom and asulfur atom are particularly preferred.

The atom having two or more bonding hand represented by La, Lb or Lc inFormula 1 are preferably a carbon atom, an oxygen atom, a nitrogen atom,a silicon atom and a titanium atom, although there is no limitation onsuch the atom. The carbon atom is preferred among them.

Concrete examples of the organic ligand represented by Formula 1 areshown below. However the organic ligand usable in the invention is notlimited to the followings.

Among the group represented by R₁₀₁ in Formula R2, an alkyl group, acycloalkyl group, an aryl group and a heterocyclic group are preferred,and an alkyl group substituted with a fluorine atom, a cycloalkyl groupsubstituted with a fluorine atom, an aryl group and an aromaticheterocyclic group are particularly preferred.

Among the substituent represented by Y₁₀₁ in Formula R2, an oxygen atomis preferable.

In Formula R2, a benzene ring, a pyridine ring a thiophene ring andfuran ring are preferable among the 4- to 8-member rings formed by Z₁₀₁and the double bonded carbon atoms.

Although concrete examples of rare-earth metal complex fluorescentsubstance having an anion ligand are shown below, the invention is notlimited thereto.

In the invention, the color conversion filter is a wavelength conversionelement for changing the color of light emitted from a light source to arequired color, which is basically a wavelength conversion elementcapable of converting the wavelength of the light from the light sourceto a wavelength longer 10 nm or more than that of the light of the lightsource. Such the color filter is practically used, for example, as afilter for color display (a color conversion filter capable of emittingblue, green and red light which is composed of strips of elements eachconverting blue light from the light source to green or red light)described in JP O.P.I. Nos. 3-152897, 9-245511 and 11-297477, a whitelight emission filter (a color conversion filter for emitting wide rangevisible light from 400 nm to 700 nm) for lighting or a back light ofliquid crystal display, a filter for partially lighting of a neon signor a meter of a car (a color conversion filter for displaying requiredcolor at a required portion).

EXAMPLES

The invention is described in detail below according to examples.However, the embodiment of the invention is not limited to the examples.

Example 1-1 Preparation Electroluminescent Element UV-1

A pattern was formed on a substrate composed of a glass plate on which alayer of 150 nm of ITO was formed (NA-45 manufactured by NH TechnoglassCo. Ltd.) to prepare an anode. Thus prepared transparent substratecarrying the transparent ITO electrode was subjected to ultrasonicwashing by isopropyl alcohol, and dried by dried nitrogen gas. Then thesubstrate was cleaned for 5 minutes by UV and ozone. Thus obtainedtransparent substrate was fixed on a substrate holder of an usual vacuumevaporation apparatus available on the market. Besides, 200 mg ofN,N′-diphenyl-N,N′-bis(3-methylphenyl)[1,1′-biphenyl]-4,4′-diamine(TPD), 200 mg of p-quaterphenyl (PQP), and 200 mg oftris(8-hydroxyquinolinate)-aluminum (Alq₃) were each respectively put indifferent molybdenum resistive heating boats, and the boats wereinstalled in the vacuum evaporation apparatus. Then the pressured in thevacuum tank was reduced by 4×10⁻⁴ Pa. The heating boat carrying TPD washeated by 220° C. by applying an electric current to evaporate TDP onthe transparent substrate with a evaporation rate of from 0.1 to 0.3nm/sec. Thus a positive hole injection layer having a thickness of 60 nmwas provided. Then, the heating boat carrying PQP was heated by 220° C.by applying an electric current to evaporate PQP on the positive holeinjection layer with a evaporation rate of from 0.1 to 0.3 nm/sec. Thusa light emission layer having a thickness of 40 nm was prepared.Moreover, the heating boat carrying Alq₃ was heated by 250° C. byapplying an electric current to evaporate Alq₃ on the light emissionlayer with a evaporation rate of 0.1 nm/sec. Thus an electron injectionlayer having a thickness of 20 nm was prepared. The temperature of thesubstrate at the evaporation was a room temperature. Then the vacuumtank was opened, a stainless steel mask having a rectangular hole wasattached on the electron injection layer. On the other hand, 3 g ofmagnesium was put in a molybdenum heating boat and 0.5 g of silver wasput in an evaporation basket made by tungsten, and they were installedin the evaporation apparatus. The pressure in the vacuum tank wasreduced by 2×10⁻⁴ Pa, and magnesium was evaporated in a rate of from 1.5to 2.0 nm/sec by applying an electric current to the boat carryingmagnesium. At the same time the basket carrying silver was heated sothat the silver was evaporated in a rate of 0.1 nm/sec. Thuselectroluminescent element UV-1 was prepared having a facing electrodecomposed of a mixture of magnesium and silver.

The element was set so that the ITO electrode was made as anode and thefacing electrode was set as cathode, and applied a direct current of 10V. Light having the maximum emission at a wavelength of 380 nm wasemitted.

Example 1-2 Preparation of Comparative Electroluminescent Element B-1

Comparative electroluminescent element B-1 was prepared in the samemanner as in electroluminescent element 1-1 except that the lightemission compound p-quaterphenyl (PQP) was replaced by 4,4′-bis(2,2′-diphenylvinyl)biphenyl (DPVBi). The element was set so that theITO electrode was made as anode and the facing electrode was set ascathode, and applied a direct current of 10 V. Blue light having themaximum emission at a wavelength of 475 nm was emitted.

Example 2-1 Synthesis of Exemplified Compound GL-10, Ba₂SiO₄:Eu²⁺

An alkaline solution was prepared by adding 150 ml of ethanol and 150 mlof water to an ammonia water containing 0.016 moles of ammonia. Then asolution composed of 150 ml of ethanol and, dissolver therein, 8.33 g oftetraethoxysilane (0.04 moles) and 0.079 g (0.2 mmoles) of europium(III) acetylacetonate complex dihydrate was dropped into the alkalinesolution in a rate of 1 ml/min while stirring at a room temperature soas to form a sol liquid. Thus obtained sol liquid was concentrated about15 times (about 30 ml) in an evaporator, and 295 ml of 0.3 moles/lbarium nitrate aqueous solution was added for gelling the sol liquid.

Thus obtained swelled gel was ripened for one knight at 60° C. in aclosed vessel. Then the gel was dispersed in about 300 ml of ethanol bystirring and separated by a vacuum filtration using a filter paperAdvantec SA. The separated matter was dried at a room temperature. Thedried gel was subjected to a heating treatment for 2 hours at 1000° C.in an atmosphere of 5% H₂—N₂. Thus 2.7 g of inorganic fluorescentsubstance GL-10 (Ba₂SiO₄:Eu²⁺ _(0.005)) was obtained which emits palegreen light under sun light.

The composition of GL-10 was analyzed by XRD spectrum. It was found thatthe main composition was Ba₂SiO₄, and the slightly containedsub-composition was BaSiO₄ and Ba₃SiO₅.

It was found that GL-10 was a green light emitting fluorescent substancehaving an average diameter of 10.5 μm and the maximum emissionwavelength thereof was 500 nm when excited by light of 405 nm.

Red light emission fine particle inorganic fluorescent substance RL-5(average diameter: approximately 0.85 μm) emitting light having themaximum emission at 610 nm (exciting light: 375 nm), and Blue lightemission fine particle inorganic fluorescent substance BL-3 (averagediameter: approximately 0.90 μm) emitting light having the maximumemission at 432 nm (exciting light: 375. nm) were prepared in a mannersimilar to that in GL-10.

Example 2-2 Improve of the Surface Property of the Fine ParticleInorganic Fluorescent Substance

To 0.16 g of aerogel having an average diameter of 5 nm, 15 g of ethanoland 0.22 g of γ-glycidoxypropyltriethoxy-silane and the mixture wasstirred for 1 hour in an open vessel at a room temperature. The mixtureand 20 g of inorganic fluorescent substance BL-10 were put into a mortarand was sufficiently ground. The ground mixture was heated for 2 hoursat 70° C. in an oven, and further heated at 120° C. for 2 hours in anoven. Thus GL-10 improved in the surface property.

The surface property of RL-5 and that of BL-3 were also improved in thesimilar manner.

Example 2-3 Improvement of the Surface Property of the ComparativeInorganic Fluorescent Substance

The surface property of Comparative fluorescent substance KX-605(Zn₂SiO₄:Mn²⁺, manufactured by Kasei-Optonics Co., Ltd.) was improved inthe same manner described in Example 2-2 except that inorganicfluorescent substance RL-5 was replace by KX-605. KX-605 was afluorescent substance having an average particle size of 7 μm andemitting light having the maximum emission wavelength of 570 nm whenexcited by light of 343 nm.

Example 3-1 Preparation of Color Conversion Filter Using the InorganicFluorescent Substance

To 10 g of the above-obtained red light emission inorganic fluorescentsubstance RL-5 improved in the surface property thereof, 30 g of abutyral resin BX-1 dissolved in 300 g of a mixture of toluene/methanolin a ratio of 1/1 was added and stirred, and the mixture was coated on aglass plate so as to form a layer having a wet thickness of 200 μm. Thecoated glass plate was heated for 4 hours at 100° C. in an oven fordrying. Thus color conversion filter F-1 according to the invention wasprepared.

Color Conversion Filters F-2 and F-3 each coated with green lightemission inorganic fluorescent substance GL-10 and blue light emissioninorganic substance BL-3, respectively, in a manner similar to that incolor conversion filter F-1 were prepared.

Moreover, comparative color conversion filter F-4 coated withcomparative inorganic fluorescent substance KX-605 was prepared in thesame manner.

Color conversion filters F-1, F-2 and F-3 according to the inventionwere almost colorless and transparent. In contrast, comparative colorconversion filter F-4 was whitely turbid and had almost no lighttransparency.

The visible light transparency of F-1, F-2, F-3 and F-4 were each 54%,57%, 57% and 4%, respectively.

Example 3-2 Preparation of Color Conversion Filter Using a Rare-EarthMetal Complex Fluorescent Substance

In 30 g of butyral resin BX-1 dissolved in 300 g of a mixture oftoluene/ethanol in a ratio of 1/1, 3 g of rare-earth metal complexfluorescent substance RE-17 according to the invention was dissolved.The solution was coated on a 80 μm polyethersulfon (PES) film in a wetthickness of 150 μm and dried to prepare red light emission colorconversion filter F-5 according to the invention.

On the other hand, green light emission color conversion filter F-6according to the invention was prepared in the same manner as in F-5except that RE-23 was used in place of RE-17.

Furthermore, green light emission color conversion filter F-7 accordingto the invention was prepared in the same manner as in F-5 except thatRE-1 was used in place of RE-17.

Example 3-3 Preparation of Color Conversion Filter Using a FluorescentDye

Comparative color conversion filter F-8 which emits green light whenexcited by blue light was prepared in the same manner as in Example 3-2except that RE-17 was replaced by 2.0 g of Coumalin 6 and 0.5 g offluorescent pigment Solvent Yellow 116.

Comparative color conversion filter F-9 which emits red light whenexcited by blue light was prepared in the same manner as in Example 3-2except that RE-17 was replaced by 1.0 g of fluorescent pigment SolventYellow 116 and 0.5 g of Basic Violet 110 and 0.5 g of Rhodamine 6G.

Color conversion filter F-1 prepared in Example 3-3 was put onelectroluminescent element UV-1 prepared in Example 1-1, and a directcurrent of 12 V was applied to the electroluminescent element in aatmosphere of dried nitrogen gas. Red light was emitted from the colorconversion filter. The luminance of the light emitted from the colorconversion filter was 26 cd/m² and the coordinate point in the CIE colorcoordinates of the light was x=0.64 and y=0.29.

Example 4-1 Evaluation of Light Emission Efficiency and Life Time of theElectroluminescent Element

The above-mentioned color conversion filters of the invention and thecomparative color conversion filter were each placed onelectroluminescent element UV-1 or comparative electroluminescentelement B-1 so that the surface of the fluorescent layer of the colorconversion filter was faced to the light emission face of theelectroluminescent element, and a direct current of 12 V wascontinuously applied to the element to continuously emit light in adried nitrogen gas at 23° C. The light emission efficiency (1 m/W) atthe start of the continuous emission and the time for 50% reduction ofthe luminance (i.e., half-life time thereof)were measured. The lightemission efficiency was described in a relative value based on theefficiency of Sample No. 7 being 100, and the half-life time ofluminance was described by a relative value, based on the half-life ofSample No. 7 being 100. Results of the experiments are shown in Table 1.

TABLE 1 Light Half-life Organic Color emission Color Time of electrolu-con- efficiency of luminance Sample minescent version (relative emitted(relative No. element filter value) light value) Note 1 UV-1 F-1 71 Red169 Inv. 2 UV-1 F-5 68 Red 156 Inv. 3 B-1 F-9 25 Red 103 Comp. 4 UV-1F-2 168 Green 186 Inv. 5 UV-1 F-4 15 Green 161 Comp. 6 UV-1 F-6 155Green 162 Inv. 7 B-1 F-8 100 Green 100 Comp. 8 UV-1 F-3 111 Blue 186Inv. 9 UV-1 F-7 108 Blue 169 Inv.

It is found from the results in Table 1 that the electroluminescentelements having the color conversion filter of the invention, SamplesNo. 1 and No. 2, are higher in the light emission efficiency and longerin the life time compared with Comparative sample No. 3. The tone oflight emitted from each of the samples according to the invention wasbetter than that of light emitted from the comparative sample.

It is found that the electroluminescent elements having the colorconversion filter of the invention emitting green light, Samples No. 4and No. 6, are considerably higher in the light emission efficiencycompared with comparative sample No. 5. Furthermore, it was found thatthe samples according to the invention were higher in the light emissionefficiency and longer in the life time compared with comparative sampleNo. 7 composed of the blue light emitting electroluminescent element andthe color conversion filter. The tone of light emitted from the samplesaccording to the invention was better than that of light emitted fromthe comparative sample Moreover, it was confirmed that samples No. 8 andNo. 9 according to the invention have the highest light emissionefficiency and working stability.

Example 5-1 Evaluation of LED Element

Color conversion filter F-1 or F-5 according to the invention were eachplaced on an ultraviolet emission LED element (UV LED Lamp manufacturedby Nichia Kagaku Co., Ltd.) so that the fluorescent substance layer wasplaced near the LED element, and an electric voltage was applied to emitlight. Red light having a high luminance and good tone was emitted.Similarly, color conversion filter F-2 and F-6 according to theinvention were each placed on the LED element and an electric voltagewas applied. Green light having a high luminance and good tone wasemitted. Color conversion filter F-3 and F-7 according to the inventionwere each placed on the LED element and an electric voltage was applied.Blue light having a high luminance and good tone was emitted.

Example 6-1 Preparation of Electroluminescent Element S—N7 UsingCompound N-7 According to the Invention

An electroluminescent element S—N7 was prepared in the same manner as inExample 1-1 except that the light emission substance p-quarterphenyl(PQP) was replaced by compound N-7 according to the invention.

The element was set so that the ITO electrode was an anode and thefacing electrode composed of silver and magnesium was a cathode, and adirect current of 10 V was applied through the electrodes. Violet lightwas emitted.

Example 6-2 Preparation of Electroluminescent Element S-A3 UsingCompound A-3 According to the Invention

An electroluminescent element S-A3 was prepared in the same manner as inExample 1-1 except that the light emission substance p-quaterphenyl(PQP) was replaced by compound A-3. according to the invention. Theelement was set so that the ITO electrode was an anode and the facingelectrode composed of silver and magnesium was a cathode, and a directcurrent of 10 V was applied through the electrodes. Pale violet lightwas emitted.

Example 6-3 Preparation of Electroluminescent Element S—B1 UsingCompound B-1 According to the Invention

A electroluminescent element S—B1 was prepared in the same manner as inExample 1-1 except that the light emission substance p-quaterphenyl(PQP) was replaced by compound B-1 according to the invention.

The element was set so that the ITO electrode was an anode and thefacing electrode composed of silver and magnesium was a cathode, and adirect current of 10 V was applied through the electrodes. Violet lightwas emitted

Example 6-4 Preparation of Electroluminescent Element S-D5 UsingCompound D-3 According to the Invention

An electroluminescent element S-D5 was prepared in the same manner as inExample 1-1 except that the light emission substance p-quaterphenyl(PQP) was replaced by compound D-5 according to the invention.

The element was set so that the ITO electrode was an anode and thefacing electrode composed of silver and magnesium was a cathode, and adirect current of 10 V was applied through the electrodes. Violet lightwas emitted.

Example 6-5 Preparation of Electroluminescent Element S—F1 UsingCompound F-1 According to the Invention

An electroluminescent element S—F1 was prepared in the same manner as inExample 1-1 except that the light emission substance p-quaterphenyl(PQP) was replaced by compound F-1 according to the invention.

The element was set so that the ITO electrode was an anode and thefacing electrode composed of silver and magnesium was a cathode, and adirect current of 10 V was applied through the electrodes. Violet lightwas emitted.

Example 7-1 Evaluation of the Near Ultraviolet or Violet Light EmissionCompound

Color conversion filter F-2 according to the invention was placed oneach of the near ultraviolet or violet light emission electroluminescentelements 6-1 to 6-5 and electroluminescent element UV-1 so as to facethe fluorescent substance layer of the color conversion filter to thelight emission surface of the electroluminescent element. The elementswere each continuously lighted by applying a direct current of 15V at23° C. in a dried nitrogen gas atmosphere.

The luminance (cd/m²) at the start of light emission and the time for50% reduction of the light were measured. The luminance of light wasdescribed in a relative value when that of Sample 701 was set at 100,and the time for 50% reduction of luminance was described by a relativevalue when the 50% reduction time of Sample No. 701 was set at 100.Results of the experiments are shown in Table 2.

TABLE 2 Luminance of Half-life Organic Color emitted Color time ofelectrolu- con- light of luminance Sample minescent version (relativeemitted (relative No. element filter value) light value) Note 701 UV-1F-2 100 Green 169 Inv. 702 S-N7 F-2 178 Green 156 Inv. 703 S-A3 F-2 456Green 103 Inv. 704 S-B1 F-2 320 Green 186 Inv. 705 S-D5 F-2 540 Green161 Inv. 706 S-F1 F-2 312 Green 169 Inv.

As is shown in Table 2, electroluminescent elements S—N7, S-A3, S—B1,S-D5 and S—F1 each using the compounds N-7, A-3, B-1, D-5 and F-1according to the invention, respectively, each emit considerably higherluminance and have a improved life time compared with electroluminescentelement using the usual light emission material UV-1 when the same colorconversion filter is applied.

Preparation of electroluminescent element using the compound accordingto the invention emitting light within the visual region.

Example 8-1 Preparation of Electroluminescent Element S—C8 UsingCompound C-8 According to the Invention

An electroluminescent element S-A3 was prepared in the same manner as inExample 1-1 except that the light emission substance p-quaterphenyl(PQP) was replaced by compound C-8 according to the invention.

The element was set so that the ITO electrode was an anode and thefacing electrode composed of silver and magnesium was a cathode, and adirect current of 10 V was applied through the electrodes. Blue-greenlight was emitted.

Example 8-2 Preparation of Electroluminescent Element S-E1 UsingCompound E-1 According to the Invention

An electroluminescent element S-E1 was prepared in the same manner as inExample 1-1 except that the light emission substance p-quaterphenyl(PQP) was replaced by compound E-1 according to the invention.

The element was set so that the ITO electrode was an anode and thefacing electrode composed of silver and magnesium was a cathode, and adirect current of 10 V was applied through the electrodes. Green lightwas emitted.

Example 8-3 Preparation of Electroluminescent Element S—F7 UsingCompound F-7 According to the Invention

An electroluminescent element S—F7 was prepared in the same manner as inExample 1-1 except that the light emission substance p-quaterphenyl(PQP) was replaced by compound F-7 according to the invention.

The element was set so that the ITO electrode was an anode and thefacing electrode composed of silver and magnesium was a cathode, and adirect current of 10 V was applied through the electrodes. Blue lightwas emitted.

(Comparison of characteristics of the compound according to theinvention with that of a known compound similar thereto)

Example 9-1 Preparation of Comparative Electroluminescent Element CF-1

An electroluminescent element having the structure shown in FIG. 101 wasprepared in the same manner as in Example 1-1.

Comparative electroluminescent element CF-1 was prepared in the samemanner as in electroluminescent element UV-1 except that a layer of NPBhaving a thickness of 70 nm was laminated at the first layer or apositive hole transport layer, a layer of Zn(BOX) having a thickness of50 nm was laminated at the second layer or light emission layer and alayer of OXD-7 having a thickness of 30 nm was laminated at the thirdlayer or electron transport layer.

The element was set so that the ITO electrode was an anode and thefacing electrode composed of silver and magnesium was a cathode, and adirect current of 10 V was applied through the electrodes. Blue lightwas emitted.

Example 9-2 Comparison of Characteristics of Triarylamine Type Compoundsas the Positive Hole Transporting Material

Electroluminescent elements 9201 to 9214 were prepared in the samemanner as in electroluminescent element CF-1 prepared in Example 9-1except that the positive hole transporting material in the first layerNPB was replaced by each of the compounds shown in Table 3.

The elements were each continuously lighted by applying a direct currentof 15 V through the ITO electrode as the, anode and the facing electrodecomposed of silver and magnesium as the cathode at 23° C. in a driednitrogen gas atmosphere. The luminance (cd/m²) at the start of lightemission and the time for 50% reduction of the luminance of light weremeasured. The luminance of light was described in a relative value whenthat of Sample 9201 was set at 100, and the time for 50% reduction ofluminance was described by a relative value when the 50% reduction timeof Sample No. 9201 was set at 100. Results of the experiments are shownin Table 3.

Compound described in J. MATER. CHEM. 1992, 2(10), 109-1110

Compound described in JP-A 10-312073

Compound described JP-A 10-101625

Compound described in JP-A 11-152253

TABLE 3 Positive Luminance Half-life hole of emitted Color time oftransportmaterial light of luminance Sample of (relative emitted(relative No. 1st layer value) light value) Note 9200 NPB 124 Blue 77Comp. 9201 QA-1 100 Blue 100 Comp. 9202 QA-2 103 Blue 112 Comp. 9203QA-3 97 Blue 87 Comp. 9204 QA-4 95 Blue 110 Comp. 9205 QA-5 90 Blue 103Comp. 9206 QA-6 87 Blue 108 Comp. 9207 A-3 185 Blue 217 Inv. 9208 A-5181 Blue 256 Inv. 9209 A-13 216 Blue 188 Inv. 9210 A-6 190 Blue 201 Inv.9211 A-18 211 Blue 175 Inv. 9212 A-19 237 Blue 211 Inv. 9213 F-1 222Blue 215 Inv. 9214 F-12 210 Blue 201 Inv.

As shown in Table 3, Samples Nos. 9207 to 9214 in each of which thetriarylamine compounds according to the invention were used as thepositive hole transport material are all have a high luminescentluminance and a long life time.

For example, it is found that the sample using compound A-3 according tothe invention having three bonding axes shows two times higher in theluminance and two or more times longer in the life time compared withSample No. 9201 using N,N,N-tri-p-terphenylamine.

Moreover, it is found that Sample No. 9209 using compound A-13 accordingto the invention which has three triamine moieties and three C₂ symmetryaxes in the molecule thereof has a higher luminance and a longer lifetime compared with Samples Nos. 9202 and 9203 in which compounds QA-2and QA-3 are used, respectively.

Similarly, the electroluminescent elements using compounds A-6, A-18,A-19 and F-1 according to the invention in the positive hole transportlayer are each have both of a higher luminance and a longer lightemission life time compared with comparative compounds QA-1 and QA-6which are benzidine (naphthidine) derivative.

In another word, it is found that the electroluminescent elements inwhich the triarylamine compound of the invention having biaryl groupcontaining two or more atrop bonding axes are used as the positive holetransport material, generally show a higher positive hole transportability and a longer life time compared with the compound having no oronly one biaryl group containing the atrop bonding axis.

Example 9-3 Comparison of Characteristics of Triarylamine Compounds asthe Positive Hole Transport-light Emission Material

Organic EL Nos. 9300 to 9312 having the first layer (positive holetransportation-light emission layer) and the third layer (electrontransportation layer), as shown below were prepared in the same manneras in the electroluminescent elements in Examples 9-1 and 9-2 exceptthat the second layer was omitted. The cross section thereof is asfollows.

Cathode (Ag/Mg) 3rd layer Electron transport layer 2nd layer Positivehole transport/light emission layer 1st layer Anode (ITO) Glasssubstrate

The elements were each continuously lighted by applying a direct currentof 15 V through the ITO electrode as the anode and the facing electrodecomposed of silver and magnesium as the cathode at 23° C. in a driednitrogen gas atmosphere. The luminance (cd/m²) at the start of lightemission and the time for 50% reduction of the light were measured. Theluminance of emitted light was described in a relative value when thatof Sample 9301 was set at 100, and the time for 50% reduction ofluminance was described by a relative value when the 50% reduction timeof Sample No. 9301 was set at 100. Results of the evaluation are shownin Table 4.

TABLE 4 Positive hole Luminance Half-life transport/ of emitted Colortime of light emission light of luminance Sample material in 1st(relative emitted (relative No. layer value) light value) Note 9300 NPB63 Blue 82 Comp. 9301 QA-1 100 Blue 100 Comp. 9302 QA-2 15 Blue 95 Comp.9303 QA-3 56 Blue 82 Comp. 9304 QA-4 89 Blue 108 Comp. 9305 QA-5 72 Blue93 Comp. 9306 QA-6 211 Blue 90 Comp. 9307 A-3 312 Blue 191 Inv. 9308 A-5256 Blue 209 Inv. 9309 A-13 271 Blue 181 Inv. 9310 A-6 288 Blue 200 Inv.9311 A-18 270 Blue 182 Inv. 9312 A-19 279 Blue 218 Inv. 9313 F-1 277Blue 210 Inv. 9314 F-12 245 Blue 232 Inv.

As is shown in Table 4, it is understood that the comparativetriarylamine compounds, NPB and QA-1 to QA-7, are all usable as thepositive hole transport material and light emission material. However,all the elements using them have a low luminance and a short life time.

Contrary, both of a high luminance and a long life time can be obtainedby the electroluminescent elements using the compound having two or morebiaryl group containing the antrope bonding axis according to theinvention.

Compound described in Appl. Phys. Lett. 55, 1489 (1989)

Compound described in Jpn. J. Appl. Phys. Lett. 32, L917 (1993)

Compound described in Maclomolecules 31, 6434 (1998)

Compound described in Appl. Phys. Lett. 67, 3853 (1995)

Compound described in JP-A 9-255686

Compound described in JP-A 10-261489

Example 9-4 Comparison of Characteristics of 5-member HeterocyclicCompound as the Electron Transportation Material

Electroluminescent elements Nos. 9401 to 9411 were prepared in the samemanner as in electroluminescent element CF-1 except that the electrontransportation material in the third layer OXD-7 was only replaced bythe compounds shown in Table 5.

The elements were each continuously lighted by applying a direct currentof 15 V through the ITO electrode as the anode and the facing electrodecomposed of silver and magnesium as the cathode at 23° C. in a driednitrogen gas atmosphere. The luminance (cd/m²) at the start of lightemission and the time for 50% reduction of the light were measured. Theluminance of light was described in a relative value when that of Sample9401 was set at 100, and the time for 50% reduction of luminance wasdescribed by a relative value when the 50% reduction time of Sample No.9401 was set at 100. Results of the experiments are shown in Table 5.

TABLE 5 Electron Luminance Half-life Transport of emitted Color time ofmaterial light of luminance Sample of 3rd (relative emitted (relativeNo. layer value) light value) Note 9200 OXD-7 121 Blue 128 Comp. (CF-1)9401 QB-1 100 Blue 100 Comp. 9402 QB-2 103 Blue 131 Comp. 9403 B-3 144Blue 417 Inv. 9404 B-1 133 Blue 325 Inv. 9405 B-7 149 Blue 401 Inv. 9406B-9 153 Blue 377 Inv. 9407 B-2 134 Blue 445 Inv. 9408 B-8 149 Blue 468Inv. 9409 B-6 138 Blue 481 Inv. 9410 B-10 144 Blue 381 Inv. 9411 F-3 133Blue 447 Inv.

As is shown in Table 5, it is found that the luminance is raised inSample Nos. 9403 to 9411 in each of which the 5-member heterocycliccompounds were used as the electors transportation material of theelectroluminescent element compared with Sample Nos. 9200, 9401 and 9402in which the usual electron transportation material. Moreover, the lifetime of the elements is considerably improved. Such the effects aresufficiently realized by the 5-member heterocyclic compounds B-1, B-3,B-7, B-9 and B-10 according to the invention each having one biarylgroup containing an atrop bonding axis. However, it is observed thatsuch the effects are further enhanced when the 5-member heterocycliccompounds B-2, B-8, B-6 and F-3 according to the invention, which have abiaryl group containing two atrop bonding axes.

Example 9-5 Comparison of Characteristics of 5-member HeterocyclicCompound as the Electron Transportation-light Emission Material

Organic EL Nos. 9500 to 9511 having the first layer (positive holetransportation layer) and the third layer (electron transportation-lightemission layer), as shown below were prepared in the same manner as inthe electroluminescent elements in Example 9-4 except that the secondlayer was omitted.

Cathode (Ag/Mg) 3rd layer Electron transportation-light emission layer2nd layer Positive hole transportation layer 1st layer Anode (ITO) Glasssubstrate

The elements were each continuously lighted by applying a direct currentof 15 V through the ITO electrode as the anode and the facing electrodecomposed of silver and magnesium as the cathode at 23° C. in a driednitrogen gas atmosphere. The luminance (cd/m²) at the start of lightemission and the time for 50% reduction of the light were measured. Theluminance of light was described in a relative value when that of Sample9501 was set at 100, and the time for 50% reduction of luminance wasdescribed by a relative value when the 50% reduction time of Sample No.9501 was set at 100. Results of the experiments are shown in Table 6.

TABLE 6 Electron Transport/ Luminance Half-life light of emitted Colortime of emission light of luminance Sample material of (relative emitted(relative No. 3rd layer value) light value) Note 9500 OXD-7 135 Blue 122Comp. 9501 QB-1 100 Blue 100 Comp. 9502 QB-2 142 Blue 128 Comp. 9503 B-3312 Blue 388 Inv. 9504 B-1 252 Blue 376 Inv. 9505 B-7 388 Blue 321 Inv.9506 B-9 400 Blue 381 Inv. 9507 B-2 501 Blue 401 Inv. 9508 B-8 522 Blue443 Inv. 9509 B-6 477 Blue 450 Inv. 9510 B-10 344 Blue 312 Inv. 9511 F-3479 Blue 405 Inv.

As is shown in Table 6, it is found that the luminance is considerablyraised Sample Nos. 9503 to 9511 in each of which the 5-memberheterocyclic compounds according to the invention are used as theelectron transportation-light emission material of theelectroluminescent elements compared with Sample Nos. 9500, 9501 and9502 in which the usual electron transportation material. Moreover, thelife time of the elements is considerably improved. Such the effects,particularly on the life time of the element are sufficiently realizedby the 5-member heterocyclic compounds B-1, B-3, B-7, B-9 and B-10according to the invention each having one biaryl group containing anatrop bonding axis. However, it is observed that such the effects arefurther enhanced when the 5-member heterocyclic compounds B-2, B-8, B-6and F-3 according to the invention, which have a biaryl group containingtwo atrop bonding axes.

Example 9-6 Evaluation of the Characteristics of 6-member HeterocyclicCompound as the Electron Transportation Material

Electroluminescent elements Nos. 9601 to 9605 were prepared in the samemanner as in electroluminescent element CF-1 prepared in Example 9-1except that the electron transportation material OXD contained in thethird layer was only replaced by the compounds shown in Table 7.

The elements were each continuously lighted by applying a direct currentof 15 V through the ITO electrode as the anode and the facing electrodecomposed of silver and magnesium as the cathode at 23° C. in a driednitrogen gas atmosphere. The luminance (cd/m²) at the start of lightemission and the time for 50% reduction of the light were measured. Theluminance of light was described in a relative value when that of Sample9601 was set at 100, and the time for 50% reduction of luminance wasdescribed by a relative value when the 50% reduction time of Sample No.9601 was set at 100. Results of the experiments are shown in Table 7.

TABLE 7 Luminance Half-life Electron of emitted Color time of transportlight of luminance Sample material in (relative emitted (relative No.3rd layer value) light value) Note 9601 QC-1 100 Blue 100 Comp. 9602 C-1131 Blue 312 Inv. 9603 C-2 185 Blue 283 Inv. 9604 C-3 133 Blue 340 Inv.9605 C-8 167 Blue 401 Inv.

As shown in Table 7, it is observed that the luminance is considerablyraised in Sample Nos. 9602 to 9605 in each of which the 6-memberheterocyclic compound according to the invention is used as the electrontransportation material of the electroluminescent element compared withSample 9601 using the usual electron transportation material. Moreover,it is understood that the emission life time of the element of theinvention is considerably improved.

Example 9-7 Evaluation of the Characteristics of 6-member HeterocyclicCompound as the Electron Transportation-light Emission Material

Organic EL sample Nos. 9701 to 9705 were prepared by removing the secondlayer (light emission layer) electroluminescent elements Nos. 9601 to9605 prepared in Example 9-6.

The elements were each continuously lighted by applying a direct currentof 15 V through the ITO electrode as the anode and the facing electrodecomposed of silver and magnesium as the cathode at 23° C. in a driednitrogen gas atmosphere. The luminance (cd/m²) at the start of lightemission and the time for 50% reduction of the light were measured. Theluminance of light was described in a relative value when that of Sample9701 was set at 100, and the time for 50% reduction of luminance wasdescribed by a relative value when the 50% reduction time of Sample No.9701 was set at 100. Results of the experiments are shown in Table 8.

TABLE 8 Electron Transport/ Luminance Half-life light of emitted Colortime of emission light of luminance Sample material in (relative emitted(relative No. 3rd layer value) light value) Note 9701 QC-1 100 Blue 100Comp. 9702 C-1 140 Blue 280 Inv. 9703 C-2 209 Blue 221 Inv. 9704 C-3 139Blue 321 Inv. 9705 C-8 205 Blue 310 Inv.

As is shown in Table 8, it is observed that the luminance isconsiderably raised in Sample Nos. 9702 to 9705 in each of which the6-member heterocyclic compound according to the invention is used as theelectron transportation-light emission material of theelectroluminescent element compared with Sample 9701 using the usualelectron transportation material. Moreover, it is found that theemission life time of the element of the invention is considerablyimproved.

Example 9-8 Example of Another Use of 6-member Heterocyclic Compounds

It was found that a high luminance and a long life time can be attainedwhen compound C-9 according to the invention was used as a fluorescentdopant together with a light emission substance such as Alq₃ comparedwith usually used quinacridone or N,N′-dimethylquinacridone.

It was found that compound C-6 according to the invention was usable asa yellow green light emission substance.

Example 9-9 Comparison of Characteristics of Stilbene Compounds as theLight Emission Substance

Electroluminescent elements Nos. 9901 to 9908 were prepared in the samemanner as in electroluminescent element CF-1 prepared in Example 9-1except that the light emission substance Zn(BOX) in the second layer wasonly replaced by the compounds shown in Table 9.

The elements were each continuously lighted by applying a direct currentof 15 V through the ITO electrode as the anode and the facing electrodecomposed of silver and magnesium as the cathode at 23° C. in a driednitrogen gas atmosphere. The luminance (cd/m²) at the start of lightemission and the time for 50% reduction of the light were measured. Theluminance of light was described in a relative value when that of Sample9901 was set at 100, and the time for 50% reduction of luminance wasdescribed by a relative value when the 50% reduction time of Sample No.9901 was set at 100. Results of the experiments are shown in Table 9.

TABLE 9 Light Luminance Half-life emission of emitted Color time ofmaterial light of luminance Sample in 2nd (relative emitted (relativeNo. layer value) light value) Note 9901 QD-1 100 Blue 100 Comp. 9902 D-1122 Blue 140 Inv. 9903 D-5 125 Blue 134 Inv. 9904 D-8 131 Blue 142 Inv.9905 D-12 140 Blue 125 Inv. 9906 D-11 158 Blue 155 Inv. 9907 D-2 205Blue 212 Inv. 9908 D-4 212 Blue 209 Inv.

As is shown in Table 9, it is observed that the luminance isconsiderably raised in each of Sample Nos. 9902 to 9908 in each of whichthe 5-member stilbene compound according to the invention is used as theelectron transportation and light emission material of theelectroluminescent element compared with Sample 9701 using the usualelectron transportation material. Moreover is understood that theemission life time of the element of the invention is considerablyimproved. Such the effects are sufficiently realized by the stilbenecompounds D-1, D-5, D-8, D-11 and D-12 according to the invention eachhaving one biaryl group containing an atrop bonding axis. However, it isobserved that such the effects are further enhanced when the stilbenecompounds D-2 and D-4 according to the invention, which have a biarylgroup containing two atrop bonding axes.

Example 9-10 Comparison of Characteristics of Metal Complex Compounds asthe Electron Transportation-light Emission Material

Electroluminescent elements Nos. 91001 to 91008 having the positive holetransportation layer or the first layer and the electron transport-lightemission layer or the second layer were prepared in the same manner asin electroluminescent element CF-1 except that the light emissionsubstance Zn(BOX)₂ was replaced by the compound shown in Table 10 andthe electron transportation layer or the third layer was removed.

The elements were each continuously lighted by applying a direct currentof 15 V through the ITO electrode as the anode and the facing electrodecomposed of silver and magnesium as the cathode at 23° C. in a driednitrogen gas atmosphere. The luminance (cd/m²) at the start of lightemission and the time for 50% reduction of the light were measured. Theluminance of light was described in a relative value when that of Sample91001 was set at 100, and the time for 50% reduction of luminance wasdescribed by a relative value when the 50% reduction time of Sample No.91001 was set at 100. Results of the experiments are shown in Table 10.

TABLE 10 Electron transport/ Half-life light Luminescent Color time ofemission efficiency of luminance Sample material in (relative emitted(relative No. 2nd layer value) light value) Note 91001 QE-1 100 Orange100 Comp. 91002 QE-2 140 Yellow 140 Comp. 91003 E-1 312 Yellow- 134 Inv.green 91004 E-6 421 Yellow- 142 Inv. green 91005 E-7 235 yellow 125 Inv.91006 E-10 329 Yellow- 155 Inv. green 91007 E-11 544 Green 212 Inv.91008 F-5 551 Yellow- 209 Inv. green

As is shown in Table 10, it is observed that the luminescent efficiencyis considerably raised in each of Sample Nos. 91003 to 91007 in each ofwhich the metal complex compound according to the invention is used asthe electron transportation-light emission material of theelectroluminescent element compared with Samples 91001 and 91002 eachusing the usual material. Moreover is understood that the emission lifetime of the element of the invention is considerably improved. Such theeffects are sufficiently realized by the stilbene compounds D-1, D-5,D-8, D-11 and D-12 according to the invention each having one biarylgroup containing an atrop bonding axis. However, it is observed thatsuch the effects are-further enhanced when the stilbene compounds D-2and D-4 according to the invention, which have a biaryl group containingtwo atrop bonding axes. The comparison is carried out on the lightemission efficiency, evaluation based on the luminance is difficultsince the wavelength of the light emitted from each of the elements areconsiderably different. The life time of the element is considerablyimproved.

Exemplary Synthesis Method of the Compound According to the Invention

2-arylphenylpridine derivative represented by Formula N1 can besynthesized by the method described in Shuichi Oi, Susumu Fukita andYoshio Inoue, Chem. Comumn., 1998, 1439-2440.

Various compounds each having a binaphthyl group according to theinvention can be typically synthesized by the course shown in Scheme 2to Scheme 5.

Synthesizing triarylamine A-18 according to the invention by the courseof Scheme 4 is shown below as an example of synthesis.

Synthesis Example 1 Synthesis of 4-bromo-1,1′-binaphthyl (Compound XX)

In a 2000 ml flask having four mouths, 50 g (197 mmoles) was dissolvedin 600 ml of methylene chloride. In an ice bath, a solution of 3.4 ml ofbromine (65.6 moles, ⅓ equivalents) 10 diluted 10 times with methylenechloride was dropped to the solution. After addition of the brominesolution, ⅓ equivalents of bromine solution was respectively furtheradded in two times while sampling the solution to confirm the reactionrate by a high speed liquid chromatography. The solution was stirred fora whole day and night and then the solvent was removed by distillationunder a reduced pressure. The raw product thus obtained wasrecrystallized using acetonitrile and subjected to 2 times of suspensionwashing. Thus 43.9 g (67.0%) of 4-bromo-1,1′-binaphthyl was obtained.

Synthesis Example 2

In a 500 ml flask having three mouths, 10 g (30.0 mmole) of4-bromo-1,1′-binaphthyl, 5.05 g (15.0 mmoles) of N,N′-diphenylbenzene,0.48 g (7.50 mmoles) of copper powder, 4.73 g (34.2 mmoles) of potassiumcarbonate and 25 ml of nitrobenzene were put and stirred at 200° C. for30 hours. After the reaction, the solution was filtered to removeinorganic substances. The filterate was washed by water and dried bymagnesium sulfate. The solvent was removed by distillation from thedried solution. Then the product was purified and separated by a silicagel chromatography using a toluene-hexane mixture solvent. Thus 5.40 g(65.0 mmoles, 43%) was obtained.

EFFECT OF THE INVENTION

The first effect of the invention is to obtain a color conversion filterusing a fine particle of inorganic fluorescent substance or a rare-earthmetal complex coordinated with an organic ligand according to theinvention. The second effect of the invention is to confirm that thewavelength of light can be converted into visible wavelength by the useof a combination of a color conversion filter according to the inventionand a known near-ultraviolet light emission organic electro-luminescentelement. The third effect of the invention is to confirm that suitablelight is emitted by a combination of a color conversion filter of theinvention and an organic electroluminescent element using a compound ofthe invention and that the light emission from such the combination hasa long life time. The fourth effect of the invention is to confirm thatboth of a high luminance and a long life time by the organicelectroluminescent element using a compound of the invention having abiaryl group in which a bonding axis capable of giving an internalrotation isomerism.

1. An electroluminescent material represented by the following FormulaA1:

wherein Ar₁₁, Ar₁₂ and Ar₁₃ are each an aryl group or an aromaticheterocyclic group; and at least two of Ar₁₁, Ar₁₂ and Ar₁₃ are each abiaryl group having a bond giving internal rotational isomerism, each ofthe two aromatic groups constituting the biaryl group having (4n+2)π-electrons in which n is a natural number.
 2. The electroluminescentmaterial of claim 1, wherein the electroluminescent material isrepresented by the following Formula A2:

wherein Ar₂₁, Ar₂₂ and Ar₂₃ are each an aryl group or an aromaticheterocyclic group, each of which has a bond exhibiting C₂ rotationsymmetry and giving an internal rotational isomerism.
 3. Theelectroluminescent material of claim 1, wherein the electroluminescentmaterial is represented by the following Formula A3:

wherein Ar₃₁, Ar₃₂ and Ar₃₃ are each an aryl group or an aromaticheterocyclic group, provided that at least two of Ar₃₁, Ar₃₂ and Ar₃₃are each an aryl group having a 1,1′-binaphthyl moiety.
 4. Anelectroluminescence element comprising an electroluminescent materialand an inorganic fluorescent substance capable of emitting light havinga wavelength of a maximum emission different from that of light emittedfrom the electroluminescent material upon absorption of the lightemitted from the electroluminescent material, and the electroluminescentmaterial is a compound represented by the following Formula A1:

wherein Ar₁₁, Ar₁₂ and Ar₁₃ are each an aryl group or an aromaticheterocyclic group; and at least two of Ar₁₁, Ar₁₂ and Ar₁₃ are each abiaryl group having a bond giving internal rotational isomerism, each ofthe two aromatic groups constituting the biaryl group having (4n+2)π-electrons in which n is a natural number.
 5. The electroluminescentelement of claim 4, wherein the electroluminescent material isrepresented by the following Formula A2:

wherein Ar₂₁, Ar₂₂ and Ar₂₃ are each an aryl group or an aromaticheterocyclic group, each of which has a bond exhibiting C₂ rotationsymmetry and giving an internal rotational isomerism.
 6. Theelectroluminescent element of claim 4, wherein the electroluminescentmaterial is represented by the following Formula A3:

wherein Ar₃₁, Ar₃₂ and Ar₃₃ are each an aryl group or an aromaticheterocyclic group, provided that at least two of Ar₃₁, Ar₃₂ and Ar₃₃are each an aryl group having a 1,1′-binaphthyl moiety.
 7. Theelectroluminescent element of claim 4, wherein said inorganicfluorescent substance is an inorganic fluorescent substance prepared bya Sol-Gel method.
 8. The electroluminescent element of claim 4, whereinthe wavelength of a maximum emission of the light emitted from saidinorganic fluorescent substance is within a range of from 400 nm to 700nm.
 9. The electroluminescent element of claim 4, wherein the wavelengthof a maximum emission of the light emitted from said inorganicfluorescent substance is within a range of from 600 nm to 700 nm. 10.The electroluminescent element of claim 4, wherein the wavelength of amaximum emission of the light emitted from the electroluminescentmaterial is not more than 430 nm.
 11. The electroluminescent element ofclaim 4, wherein the wavelength of a maximum emission of light emittedfrom the electroluminescent material is within a range of from 400 to430 nm.
 12. An electroluminescent element which comprises anelectroluminescent material and a rare earth metal complex capable ofemitting light having a wavelength of maximum emission different fromthat of light emitted from the electroluminescent material uponabsorption of the light emitted from the electroluminescent material andthe electroluminescent material is a compound represented by thefollowing Formula A1:

wherein Ar₁₁, Ar₁₂ and Ar₁₃ are each an aryl group or an aromaticheterocyclic group; and at least two of Ar₁₁, Ar₁₂ and Ar₁₃ are each abiaryl group having a bond giving internal rotational isomerism, each ofthe two aromatic groups constituting the biaryl group having (4n+2)π-electrons in which n is a natural number.
 13. The electroluminescentelement of claim 12, wherein the electroluminescent material isrepresented by the following Formula A2:

wherein Ar₂₁, Ar₂₂ and Ar₂₃ are each an aryl group or an aromaticheterocyclic group, each of which has a bond exhibiting C₂ rotationsymmetry and giving an internal rotational isomerism.
 14. Theelectroluminescent element of claim 12, wherein the electroluminescentmaterial is represented by the following Formula A3:

wherein Ar₃₁, Ar₃₂ and Ar₃₃ are each an aryl group or an aromaticheterocyclic group, provided that at least two of Ar₃₁, Ar₃₂ and Ar₃₃are each an aryl group having a 1,1′-binaphthyl moiety.
 15. Theelectroluminescent element of claim 12, wherein the wavelength of amaximum emission of the light emitted from the rare earth metal complexis within a range of from 400 nm to 700 nm.
 16. The electroluminescentelement of claim 12, wherein the wavelength of a maximum emission of thelight emitted from the rare earth metal complex is within a range offrom 600 nm to 700 nm.
 17. The electroluminescent element of claim 12,wherein the wavelength of a maximum emission of the light emitted fromthe electroluminescent material is not more than 430 nm.
 18. Theelectroluminescent element of claim 12, wherein the wavelength of amaximum emission of light emitted from the electroluminescent materialis within a range of from 400 nm to 430 nm.
 19. An electroluminescentelement comprising an anode and a cathode and a compound, represented bythe following Formula A1:

wherein Ar₁₁, Ar₁₂ and Ar₁₃ are each an aryl group or an aromaticheterocyclic group; and at least two of Ar₁₁, Ar₁₂ and Ar₁₃ are each abiaryl group having a bond giving internal rotational isomerism, each ofthe two aromatic groups constituting the biaryl group having (4n+2)π-electrons in which n is a natural number.
 20. The electroluminescentelement off claim 19, wherein the compound is represented by thefollowing Formula A2:

wherein Ar₂₁, Ar₂₂ and Ar₂₃ are each an aryl group or an aromaticheterocyclic group, each of which has a bond exhibiting C₂ rotationsymmetry and giving an internal rotational isomerism.
 21. Theelectroluminescent element of claim 19, wherein the compound isrepresented by the following Formula A3:

wherein Ar₃₁, Ar₃₂ and Ar₃₃ are each an aryl group or an aromaticheterocyclic group, provided that at least two of Ar₃₁, Ar₃₂ and Ar₃₃are each an aryl group having a 1,1′-binaphthyl moiety.